small objects like stamps,coins, and jewelry.

More or less any camera on a tripod in a window on a sunny day - you will probably have to crop the image on a PC. This doesn't matter because images for Ebay don't have to be good enough to print at poster size.

focus as low as 0cm

I find it is best not to rest the lens front element on the object being photographed. I'd not worry about minimum focus distance too much, any current camera with a standard lens will most likely do all that you want.

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Updates

Here's some rushed shots with a few cameras I had to hand. An old point & shoot compact, an old entry level DSLR and a new small format Compact System Camera - not in that order - all with standard lens, at night on a desk, illuminated just by an anglepoise lamp. I used a tripod.

The US 1 cent coin has diameter about 1.9 cm (3/4") I shot from 10-20 cm away. On my computer screen the cropped images are about 8x life size. The worst shot was taken with the arguably best camera (I rushed and was sloppy).

With a little time and attention I could probably have got much better pictures but if I was selling this coin on Ebay I think at least two of these shots would be OK.