I am not familiar with the newer models so I can't be too specific on any recommendation in that respect.

I have a Nikon Coolpix 990 which I got when they were first introduced in May of 2000. Paid 999 for it. 3 mpxls and has served me very well over the years. Most of the time I would use it at 1024x768 in order to get the most use out of it. I compromised there as I could get a good number of pictures on 1 card. Compact Flash was really expensive then and 64meg was all I could afford. I could go to Las Vegas and take about 170 pictures on that card and the other cards that I got with the camera. Now I shoot at the full 3mpxls since CF cards are much cheaper and I now have 128, 256 and 512 cards. Since then I have replaced the CP990 with a Nikon D100 Digital SLR. I still use the Coolpix for travel stuff where I don't want to or can't take the larger much more expensive outfit. I also use the Coolpix for photographing checks, documents etc. I don't even use my scanner anymore unless I need something specific that has to be done on a scanner. Similar to Photocopying. For general copying of stuff, like my parent's Medicare Cards etc. or, as I said Checks and Order forms from my photo or video orders.... I just snap off copies with the Coolpix. So much quicker and I think better quality in some cases.

I also, still use the Coolpix for work on my telescope. It has a threaded lens that can be adapted to the eyepieces of the telescope, is much lighter weight so as not to throw the scope as much off balance.... The battery door broke but I devised a metal plate that goes over the bottom of the camera and the camera is still going strong.

As for what you would need for shooting simple pictures for ads I would look for the following.

Macro for Jewelry, small items, chips, tokens..... This allows you to set the camera closer for more detail. The camera will then have the ability to focus closely on small objects. Problems with MACRO are often that you are too close for flash to be effective. The light from the flash may be too bright and will often give poor results. Shadows can also become extreme or non existant. On the opposite, note that your on camera flash is not that powerful. Thus taking pictures too far away may also cause problems, this time with uneven dark results.

Get something that allows the use of an external flash. My Coolpix didn't have a shoe (flash mount) but had a socket where you could take a flash and attach it to the camera via a wire. You could attach it to the camera using an optional bracket or you could mount it off the camera on a tripod or lighting stand. Mounting the flash off the camera is often preferable. Especially with tokens etc. where the relief of the surfaces and details can be enhanced with some sidelighting. Set a desk lamp on your subject from one side and use the flash to "FILL" the other side. The blue from the flash can be balanced by the orange of a single bulb. With Sidlighting, it allows shadows to fall INSIDE the details making them more noticable. Having the lighting straight on can fill the detail and make the details less noticable and your subject appear more flat.

For small stuff, I would set up a neutral area where you can set up items to be photographed. A neutral backdrop etc. If you are using automatic exposure, white balance.... A medium gray is best since it won't shift the color (white balance) of your subject and light and isn't too dark or too light to change your exposure. White will often make pictures darker since the light reflected from flash gets bounced back in higher quantities fooling the camera into thinking the picture is too bright. The exposure will then darken. Black makes your pictures lighter for the opposite reason. Auto exposure will get less light returned from the subject and that large quantity of black will make the camera lighten the picture up.

Colors work similarly with auto white balance. Yellow tones will often cause the camera to add too much blue and blue will add more yellow. Green will cause the camera to add megenta (pinkish purple). Red will cause often cause the camera to add some Cyan (bluish green). All the opposites apply.

For reference here is a chart.

Red - Cyan
Green - Magenta
Blue - Yellow.

Grey is a mid color and represents ALL colors in equal quantities and is neutral in brightness (halfway between black and white). It is best to set your exposures and white balances to a neutral gray card. If you shoot in manual settings, set the camera up zoomed into a gray card over your subject. Then you can use any colors you want. All this can similarly be applied to scanning except I don't know if scanners can be set manually. If you add colored backing papers to your scans you will encounter similar effects.

If you want the most flexibility get a camera that offers manual settings as well as automatic.

I would think that 3, 4 or 5 mpxls is more than sufficient for personal vacation shots, family snapshots or definately overkill for your ads. However, get something that will fulfill your personal needs as well as your ebay stuff. Internet photos are not very demanding. Any digital camera that offers autofocus, macro, automatic settings, USE OF AN EXTERNAL FLASH, etc. will serve good with Auction ads.