Lanefan
Victoria Rules
You need to a) randomize what's available at any given time and b) limit the number; this to reflect the idea that what comes on the market isn't predictable and there isn't that much of it.For me, and this is purely my own preference, I detest buying magic items. It's so pointless. The party buys magic items that give the most bang for the buck. So, the DM just adjusts the monsters to the new math because the DM doesn't want the party steam rolling encounters. Which means the party buys more items that give more bang for the buck and the treadmill just churns.
I really, really wish there was a way to just not have magic items for sale. I think my next campaign will be that way. Magic items can be made, but, never for sale, they are just too rare.
I'm not talking about common magic items, they aren't the problem. But, it's so incredibly boring to see the same five or six magic items get bought every single campaign.
Not sure how you hand out magic items in the adventures you run, but if you use any sort of random creation or rolling for them, after a few adventures you can give yourself some idea of the sort of things that might be on the market simply by keeping an eye on what the PCs are selling off. If the PCs are selling these things it's a good bet other parties are selling vaguely similar things, though probably not exactly the same. Then there's the random factors of:
--- items commissioned but never picked up, being sold by their creators to recoup the expense of making them
--- estate sales and the like
--- retiring adventurers cashing in by selling their adventuring gear, including many of their magic items
End result: whenever a party gets to a town or city and asks me for a "shopping list" I quickly roll to give myself an idea of how many items are available (that they're likely to learn about, assuming they ask around), tell my spreadsheet to randomly generate that many items, and print out the list. I then curate the list a bit, mostly to remove cursed items, and that's what's available for them to buy. Takes me maybe 30 seconds plus however long the printer takes to do its thing.
Sometimes someone lucks out and can buy exactly what the character wants. Most of the time, though, most of the items for sale are ignored.