[Eru]

What I used to do is make a rune to various shops, then I had a macro that would recall, target the rune, wait a few seconds, then say "Vendor-Name Buy" for all the vendors in that area, then go on to the next place. Combine that with the buy agent in Razor and that will let you stock up on individual items. I had one for Mage shops and alchemy shops mostly, but I would sometimes make specific ones for other items.

The only problem is if the NPC names change but that doesn't happen very often.