One person in our group ran their first game under the impression (from the wizards boards) that magic shops made no sense and then used the treasure tables to exclusively roll treasure. We someone how came out both way, way way above WBL, but also completely worthless thanks to having zero weapons or armor we could use or that had effects that mattered.
Oh no "somehow" about it. This is actually typical. You can't randomly roll treasure in 3e or PF1 and expect it to come out balanced. It doesn't help that a lot of classic items have bloated costs if they do more than one thing, even if the individual functions are not that great- just look at how much a Rod of Lordly Might costs.
While a "magic shop" doesn't make much sense (I mean, how do you afford to keep anything in stock, let alone security?), in my games, I extrapolated the existence of guilds that would have crafters able to make things to order, with half the money up front. Players could either wait for items to be finished, or hope to pick up their upgrades between adventures.
And if they didn't return, well, the cost of the item was covered, so it could theoretically be sold to someone else.
(In one adventure, the players actually discovered the secret of how the guilds could afford to BUY magic items- they had a pet Rust Monster that, after it destroyed a metal magic item, left behind magic dust that could be used to make other items. I got the idea from White Wolf, since Changeling and Mage have ways to find raw magic in solid form, which is called Dross or Tass, but I eventually adopted the 4e term, "residuum").
Of course, the real problem was PC crafters. The xp cost was not really a deterrent when you realized you could outfit yourself in magic swag for half the cost, and if you ended up lower level than the rest of the party, you'd get more xp from adventuring. Busted!
And then Pathfinder thought "well, we'll get rid of xp costs, and just force people to make difficult Spellcraft checks". Poor, innocent, Paizo, failing to realize how easy it is to get a bloated skill check, lol.