Which older dslr to buy?

Just for fun and some experimenting I was wondering what are some fo the best or better older dsrs preferably 6 MP and up but if there's one that is superb that is under go ahead recommend it. I just want to add to my collection lenes and brand are not a big deal as I do have Nikon an Canon as well as other leses the only concern is price. I do not want to pay the same price as a brand new DSLR!
Thanks in advance!

Added (1). Ok so i see its Nikon… D100 or D70? All around which one is going to give me better picture quality or a more "professional" look when it comes to image quality?

The Nikon D70 was a significant hallmark in Nikon's camera lineup.

http://bythom.com/D70REVIEW.HTM