I would only buy a camera that can shoot in RAW format.
I would also get a photo tent kit as suggested by others. Make sure it has decent lighting.
I would also buy a good sturdy tripod.
I would get a DLSR of some type that has full manual settings.
Normally I prefer a fixed prime lens for my photography or my trusty 70-200 f.28, but in your case a zoom lens might be fine since you probably want a higher aperture anyways. If you get an APSC DLSR and use something like a 24-70 lens from a full frame camera. That'll get you in the proper focal range for product photography (roughly 40mm to 110mm equivalent range).
I would sign up for DPREVIEW.com and jump on their forums. They actually have protographers that do product photography for a living and can give you very specific suggestions.