Used Subal for D70 http://www.camerasbelow.com/Products/Underwater_Cameras_Used.htm
$300
Underwater photographers are famous for buying the latest and greatest and selling the old stuff dirt cheap.
Personally I keep mine. I still have a subal for a nikon f100 that I have not used in 4 years with 2 strobes.
Look for used SLR’s and housings, you won’t be disappointed.
The new Subal housings can’t use the old ports so even ports are out there cheap.