These 2 links are random generators. These generators have been a great help to me in making my own towns, shops, treasure etc. If I had to name a drawback its that by being non system specific they do not have a lot of material from the splats. However, if you have an item you want you can always swap it out with an item of equal value from the randomized list (or just add it on top). Don't let that sway you away though, these are still MUST HAVE links.
This one has a Magic Shop & More. This one can separate by size of town and the type of shop you are at. (ie, alchemist shop, weapon shop etc. In addition to magic shop, this 2nd link can also be used to randomize treasure or even towns & NPCs (Names/race/levels etc, but it does not stat out their character sheet for you). If you are making your own town this link is a MUST!
This one is strictly a Magic Item Shop generator. It can be used to breakdown how much is available by size of the "town" or even customize your own shop without caring about the suggested town size limits. While not as many generators as the first link, it lets you break down by what type of magic item you want (wands/scrolls/major/minor etc..) & you can select LOTs of Magic Items
Hope this helps!