There isn't such a thing as saving money by buying used. Used cameras cost far more than the new ones, and the residual affect of this fact keeps used ones from saving you enough money to compensate for the relative lack of resolution, feaures, and image quality. If it's enough cheaper than a new unit to appear attractive, it will probably also sacrifice enough utility to make that a moot point.
What I recommend is a FZ-30 Panasonic. While not a SLR, it offers a SLR-class lens that with the addition of a wider-angle attachment lens can carry the full burden. The image quality, speed, and versitility of the FZ-30 all rival inexpensive SLRs. Only the low-light performance is notably worse, but when you are saving thousands, you can get over this. And at least you have effective IS to help compensate.
A decent DSLR costs no more than a FZ-30 these days. For the back. But if you want real glass, the price tag balloons. The inexpensive autofocus DSLR lenses aren't as good as the Panasonic's Leica, and ones that are cost a fortune (per lens, and there are a bunch to buy because few rival the Panasonics 12X zoom range). If you have the money, a D50 or D70 Nikon is great, and the Canon EOS Rebel XT and 20/30D series are tremendous units. Just be prepared for the fact that you will spend thousands before you gain the function (low light performance aside) that a FZ-30 wraps up in a neat $550 box.
It all depends on how much money you've really got to spend. If you've got the cash, buy a Canon 30D and some quality glass. Don't expect to run into such at the pawn shop, though.
