Taking pictures for selling on ebay is everything. I know when i shop on ebay i will not buy the item if there are no pictures.
When taking pictures on for ebay you dont need a $1,000 or even a $200 one.
2 mp is also more than enough. When looking for a camera just make sure it has macro (for up-close shots) and optical zoom. Make sure you set the camera for low resolution so they load faster for people without high speed internet.
Stay away from flash when taking your photos as this will distort your picture significantly.
Also a good scanner is very important for coins, trading cards, and any thing else small. A scanner get alot of detail is pretty inexpensive.