My biggest problem here is the removal of magic items as purchasable- especially if you've been doing it already and players expect it. Of course talking with your players would be advisable, but I can imagine all sorts of objections.So first step to this issue: identify the behavior you want. What do you, the GM, want characters to spend wealth on?
I think for the 1, you need to use a carousing table- there are lots from other games. And carousing should have mechanical impact- again, there are games out there with this.
- Is this Sword n Sorcery where they spend almost all of it partying, living it up, and then it's time to go on another adventure because they're broke?
- Do you want them to invest in the narrative by funding causes/factions/etc that they care about?
- Do you want them to invest in the world by building a stronghold and being responsible for an area, guild, etc?
For 2, I suppose patrons, guilds, etc are the way to go. Organizations- again, with mechanical bonuses. I know 5e has some but I've heard they're weak.
3, there's Strongholds and Followers and A5e's strongholds.
BUT again, you really need to nix gold-for-magic items if any of these are going to work. Either that, or bribe/hope/ask/initiate players to participate so other players see that they can get cool things by engaging with them.
Maybe the first taste is free, that sort of thing
Plus, my biggest issue would be that it's already been established in the setting... How to undo that, how big of a retcon is it and is it feasible... That's the problem I'd face. And sticking by my guns
Already I want to say "ok uncommon items are around occasionally but nothing higher is found for sale." But.. that leaves the door open