I made my first steps in 'serious' digital photography with a used Nikon D1.
I have pretty good experience with buying used gear at
B&H, I believe other reputable stores should also be the same (
Adorama, others...).
Here's what I could see today at
B&H used equipment catalog (and I consider good cameras):
DSLRs:
Nikon D40 + 18-55mm lens @ $349
Note on the D40:
B&H state 'email for condition' - do that!, on most other items they have 0-10 condition figure, I'd buy anything that's 8+ or 9 without hesitation, perhaps 8 too.
Canon EOS 350D @ $269, and a (separately sold) used
EF-S 18-55mm lens @ $129
Good non SLR digital cameras:
Sony Cybershot DSC-F828 @ $329
Fuji FinePix S6000fd @ $179
As a newbie it's hard to tell if you'll want to invest more money and improve your system down the road, if you believe this will happen than SLR is the better way to start, there's always room to grow when you do have the budget.
Nikon and Canon have the best DSLR lens collections (including third party makers like Sigma, Tokina etc) making them a favorable starting point IMO.
Generally I've been able to find some good deals at their used equipment store, you do need to be patient though, it sometimes takes a while for a good piece of equipment to show up there...