I have to admit that I cringe a little whenever I see the substructure of the modern consumer economy replicated in settings where it is totally inappropriate, whether post-scarcity science fiction settings or fantasy settings that should by all rights be cash-poor economies founded on the ownership of real and movable goods. In particular, the abundance of cash, the commodity fetishism in trade systems, and the catalogue-like nature of gear lists all tend to be things that I wish it were easier to do without.
I don't blame game designers for putting these structures in, since they operate on an already-existing understanding of value, particularly cash. Getting cash is so much a part of modern existence that it can be placed into a game world as an obvious motivator for PCs to do things. This is true even in later editions of D&D, where the fungibility of cash is extended to magical items so that there is no discontinuity in the value of things. Unlike a lot of other people, I am not opposed to the purchase and sale of magical items, as I can't see a logical reason they wouldn't be absorbed into the economy, especially if they can be created in any sort of reliable way. I think that it's a natural extension of another problem, the abundance and value of cash, rather than the core of the issue itself. If you want to get rid of magical item shops, get rid of cash.
I think there are two possible ways one can go about this, at least if history and political economy are any guides. The first is a gift-based economy, the second is a debt-based economy. Neither is exclusive, either with one another or with a cash-based economy, so it you can experiment with overlapping them until you find the balance that best suits you. For the rest of the post, I'm going to discuss possible ways of using gift-based economies and debt-based economies in your games and settings.
Gift economies are oriented around the accumulation of social prestige by the production and distribution of goods. This usually takes the form of ritualised gift exchanges like potlatches whereby individuals or collectives (like families or tribes) offer gifts to one another under a principle of escalation, where simply meeting the gift given to one is insufficient for satisfaction - one is obligated to outdo the gift. Homeric and other ancient Greek literature is filled with these kinds of exchanges, though often the gift exchange goes beyond material goods into favours, services and quests. In societies where this kind of economic system is practiced, reciprocity is extremely important - individuals in the historical record have committed suicide over being given gifts that they felt could never repay.
There are a number of possible ways to make this work. The first is to play on the PCs' desire for respect from others. While not everyone has this motivation, many people do, and it's common enough that it forms a workable basis. PCs should understand from the get-go that they will receive items from others as gifts, and in turn will be expected to give items to others. Refusing to give something to someone who asks makes the PC look poor and weak, while giving gifts even when not request makes them look powerful and rich. If NPCs act appropriately based on PC choice here, one can get pretty far. You can tie this in with independence as well - PCs in gift economies who constantly take and never give will be seen as and treated as the dependents of the people giving the gifts to them. If they wish to become mature adults worthy of respect in the eyes of others, they must give far more than they take.
The second element is to give the PCs things that are not directly useful, but are valuable. For example, a PC probably doesn't need 20 blankets, so if they are given them as a gift, there's an obvious incentive to pare it down to a manageable number by giving them to others. Enforcing encumbrance, especially on highly mobile PCs without a home to store all this stuff at, will help them to decide what items are essential, which are useful enough to put up with the hassle of transporting, and which should be given away. Food items and other consumables are particularly common gifts in real gift economies, often combined with a cultural injunction to consume the items once given. Spoilage and rot encourage the PCs to then share the food with anyone they can and get gratitude for it rather than hold onto it.
Another way of dealing with this is specialisation of function. This is extremely common in groups with specialised religious and technical personnel (priests and smiths). One gives gifts to the specialist even when one doesn't require their services, so that when you do need them, you are a high priority (for magical healing, for getting a new sword, etc.) over everyone else making the same request.
The third element is to emphasise the distance between barter and gift-giving. In gift economies, barter is usually reserved only for complete strangers and antagonistic groups. By insisting on a barter-like exchange in societies like this, you are telling the other person "You are a stranger, possibly even an enemy, in any case certainly no one with whom I can have a relationship with". Gift-giving is a fundamentally temporal relationship. It says "We have known one another long enough to trust and care about one another, and will continue to do so in future". To reinforce this, recurring NPCs to exchange goods with are key. PCs in a gift economy should belong to a community, whether a tribe, manor or village, with recurring individuals who they can develop these kinds of relationships with.
The game mechanical tools you need to track this are varied. I encourage the use of something like a dice map to determine what any subgroup within the overall community the PCs belong to has at hand at any given moment. My own nomad starting gear dice map and nomad family generation dice map are intended for just this purpose.
Debt-based economies are somewhat similar to a barter-economy, but often involve a formal tracking system that allows for temporal distance between one side of the exchange and another. In the real world, our modern debt-based economy relies on credit scores, loans asset to liability ratios and other complex financial tools to track how much one is indebted to others, how likely one is to repay the debt, and when one must repay it. In ancient times, this took the form of a centralised tracking authority, often the servants of a king or local warlord, who operated a common market to which various individuals and groups would come to obtain goods like metal tools or weapons, livestock, seedcorn, luxuries, etc. that they couldn't produce themselves. Usually this is combined with taxation in the form of labour, where individuals who use the common market must offer compensation for it to the authority, though sometimes goods may be exchanged instead as well.
Without claiming to be an expert on it, I'm given to understand that Mesoamericans and Mesopotamians both used variations of this system, as did medieval manors for their internal peasant economies. In this kind of system, the PCs bring back the haul from their adventures, hand it over to middlemen, and in exchange have an open line of credit for the goods they want without ever touching money. The reliability of this system requires the trackers to be upright and honest, which may or may not be the case. The debt-based economy still avoids cash, and leaves PCs relying on barter whenever they are dealing with situations outside the market operated by the authority. There may even be multiple such markets in operation by different authorities which they must deal with.
This kind of debt-based economy requires a home base the PCs return to, or at least a site for a market which will recur in the game. It also requires some sort of enforcement mechanism, either guards or magic or something else of similar threat, so that PCs don't simply break its laws constantly by taking what they want and fudging the records. Otherwise, I think this system is similar enough to modern ones that PCs will have an easy time figuring it out.