I know there are prices for items in the manual, but I don’t think they could buy anything in the manual could they?
Here’s a handy guide to population size and what might be available
Basically how large a settlement is determines what you can buy there. There’s a cap on what they might have available determined by that.
Available Magic Items
Community Size Base Value Minor Medium Major Thorpe 50 gp 1d4 items — — Hamlet 200 gp 1d6 items — — Village 500 gp 2d4 items 1d4 items — Small town 1,000 gp 3d4 items 1d6 items — Large town 2,000 gp 3d4 items 2d4 items 1d4 items Small city 4,000 gp 4d4 items 3d4 items 1d6 items Large city 8,000 gp 4d4 items 3d4 items 2d4 items Metropolis 16,000 gp * 4d4 items 3d4 items
* In a metropolis, nearly all minor magic items are available.
Now, these are just guidelines—you can fiddle with this any way you like as GM—or you can have an area that specializes in a particular type of magic but is opposed to others. Magic items that are necromantic in nature, or even charisma boosting items may be seen as illegal or possibly immoral. Not everyone carries everything, and some items might not be out, and only will be if a shop owner actually likes you.
Shops work in Pathfinder a bit how real world shops do rather than video game shops. So it isn’t about shopping via the manual. And it isn’t quite like shopping at Walmart either. They don’t have places like this.
How I work it is this—Shops can and do specialize. General stores for adventurers might have a little bit of everything, but it doesn’t mean that they will have anything other than healing potions, and you might have to go to the potion shop for anything else, and so on. A town can be known for potions, and have more expensive items of that than you might expect for their size, but could lack in all other magic items.
Every shop and settlement is different. Some shops will only carry mundane items, or be geared towards adventurers and so on.
I look at the types of items to see if they make sense, even if they are mundane. One example—a masterwork or even regular lockpick set. In the real world lock pick sets (until just recently with the advent of the internet) were actually not that easy to get. 10-20 years ago here in the real world you could not pick them up just anywhere. If you were a shop owner in a kind of medieval setting, would you be selling them?
In a rough-ready boarder town would a shop carry a parasol? How likely are most shops to carry a disguise kit? Even if they are just 200 gp…
The quick and easy thing is to just set the gold amount depending on the place (population, if the area has fallen on hard times can be your determiners), and it makes your life a little more difficult if you have to make up a list for every town.
The easy fix for me as a GM is not to make up a list for every dang place. The players give me their wish list when they get into town, and then I let them know what’s available and what isn’t. It has to make sense for the place that they are in, but I start by saying this looks like the kind of place where it would be unlikely that there’s anything over 200 gp for items, and even on the lower ones there’s just no guarantee that the shops will have everything. In the olden days this actually was how grocery shopping worked—you didn’t walk down the aisle and browse, you handed the stock boy your list, and he got your items. If they didn’t have something, they would apologize, and sometimes bring out things they did have that were similar in the hopes that you would buy it. And if you would be in again, and said you wanted an item they didn’t have, they’d see about ordering it.