Hmm…under 400 bucks will be tough. But there is always ebay or craigslist.
One thing you could do is go to QVC.com. They sell good DSLRs through their site and you can pay monthly. Might help you if you decide to get a more expensive one.

You’ll most likely have to go older for that price. It can be done, just don’t expect to find any of the current models.

I got mine for $350 on Craigs List. I have seen them as cheap as about $320 but it’ll be tough to do much better than that. You will need a lens, too—even the stock lens is not cheap.

@Kokoro what do you need the camera for at your job?

What do you want to photograph? Unless you actually need a DSLR I would recommend a good compact such as Nikon SX 200 which is 12.1 M.P, has 12X optical zoom + 4X digital zoom and on macro will focus down to 1.7cm, It has from fully auto to fully manual and will fit your budget.

$400 will not buy you a DSLR with equivalent features or quality, it would just buy you a basic lens. Add to that $800 for a reasonably decent body and you are talking about 3 times your budget. Buy a cheap DSLR and that is exactly what you will get!