Restocker is a project mainly written in Lua, it's free.
A world of warcraft addon that automagically restocks your class reagent supplies. It will warn you when you are low on reagents when away from vendors and when you are talking to one that has something you are missing it will buy it.
Worth mentioning that this addon does not restock anything at this point. Quit playing wow again, not likely to get developed but feel free to fork and create! :-)