I haven't bought from buydig.com but I have bought from beachcamera.com which is supposedly the same place, and they were excellent. Terrific price and very quick shipping.
You probably need to be a little more specific... how many lenses do you hope to get for your $1,000? Do you have any specific features in mind?
All DSLRs are excellent and all have strong and weak points (most of which are pretty minor.) Under $1,000, you're looking at a Pentax, Olympus, Sony, Nikon, or Canon DSLR. If you currently have a 35mm SLR, you may want to stick with the same brand, to re-use your existing lenses.
The cheaper ones are the Pentax K110D and K100D, the Nikon D40 and D50, the Canon Rebel XT, and the Olympus E500. In that field, you'll probably looking at anywhere from $430 to about $600. To go higher, you'll looking at the Sony Alpha, Canon Rebel XTi, or Pentax K10D - those are probably around $750-$1,000. You'd probably be best to stick with the lower-end ones to give you more elbow room for lenses.
The best bet is to read some reviews. Here's some from DPReview:
Pentax K100D
Canon Rebel XT
Nikon D50
Olympus E500
Other reviews sites include Steve's Digicams, Megapixel.net, etc.
Out of that group, I really think that the Pentax K100D offers easily the best value - it has the best image quality you can get from a 6mp camera (and is virtually identical to the 8mp Canon), it's got a good kit lens, it's available for very cheap ($513 after rebate), and best of all, it's the only one in its class with image stabilization in the body. (This is one area that DPReview didn't seem quite as impressed with as many others - most owners have found that it can help dramatically.) For the others, you'd need to buy a lens with IS, which will put you over your $1k barrier.
There are many DSLR threads on here as well with lots of good information.
There are all excellent, though, and whichever choice you make, you'll probably be very happy.