I agree with the general consensus of this thread...either Nikon or Canon. Personally, I've been shooting with a D40x the past two seasons. I recently purchased a D90. The main reason was so I can AF with my 50. I have the "cheapy" non motorized version, which if I recall correct, can be had around $100. With that lens and the kit 18-55, on my 40x, I've been able to pull off shots like these...
I would also recomend scouring the pages of
www.kenrockwell.com . Lots of excellent info, in a very laymens term manner.
Adorama, bhphoto, Ritz camera, are among the more reputable options. If you choose to purchase from Ebay, be very careful. I do know Adorama has auctions there as well as Cameta Auctions. Personally, as far as Ebay goes, I wouldn't be much inclined to trust any others.