Those two links together should have all the info you need, so the frustrating part is that it is not consolidated. But the link krischan gave will tell you what vendors can sell what base items, and the link you have will tell you what mods can spawn at what level. I copied the latter into an excel spreadsheet, so that's one way to answer your question.
Several months ago I started to bend my mind and efforts towards making a comprehensive shopping guide, but alas I just do not have the gumption (or time) to tackle something like that. It was part of my "I'm learning Microsoft Access so let's make a D2 database!" drive that petered out a while back.
Yeah I have both of those sites, I was just hoping someone had compiled like an excel version or something so that one day when those sites are gone, it will still exist. I don't know how or I would lol