You can buy everything for a retro on hidplanet.com. We also seel brand new equipment as well as have a Sell/buy used section. You can retro pretty much any projector into a Gen 3 teg, depending on how hard you want to work for it. We also give you the oppertunity for us to handle your retro from start to finish so that you don't have to deal with the work involved.
Cheap and HID, don't go hand in hand. You get what you pay for.