here are some dj's i've found:

Commencal Max Max- single speed, full rigid, $599 msrp
Giant Brass 1- geared, 100mm fork, full disc, $650 msrp
Haro Steel reserve 1.2-single speed, 80mm fork, rear disc, $675msrp
khs dj 200- geared, 100mm fork, full disc, $749 msrp
kona shred-geared, 100mm fork, full disc, $749 msrp

Healthy Habits is a haro dealer, and Bike and Hike can get you a Giant. The others you're gonna have to hunt around for online.

I have a khs that I bought on ebay. I beat the crap out of that thing, and it has held up pretty well. I'd check craig's list too. I've seen Specialized P2's here and there for under $400. It's going to be difficult to find a lbs(local bike shop) with a dj in stock.

Hope this helps at least a little.

-HW