For Amazon purposes, he doesn't need anything that produces high resolution images. His cellphone is plenty good enough, provided he uses good lighting (especially for black items), a clean, uncluttered background, and multiple angles.
For Amazon, a cheap light tent, a couple of white balanced LED hot lights, and an iphone would do the job nicely. Amazon requires the background to be pure white, the product to fill the frame, and he entire product, from front to back, to be in focus.
Surely there are adequate P&S cameras less expensive than an iPhone ...
Get an old entry level DSLR with the original kit lens, like a Rebel XT or something. You can probably find one for less than $200 that will take spectacular pics for that purpose.
A bridge camera would have the close up/ macro ability to shoot small items, and enough resolution for great pics for that purpose.
Another plus with a bridge camera is that the smaller sensor will give you more depth of field, aka make the whole item in focus at medium apertures.
Try to find one that has good control options re aperture, shutter speed and maybe manual focus as well. Image stabilization helps too unless you are planning to use a tripod.
Good used "bridge" level cameras sell on Amazon and eBay regularly for around $50-60.
