Good entry level DSLR which would take a 50mm Nikkor lens?
Please help me find one! Under $600
Any Nikon entry level DSLR.
If the lens you have is an AF-S lens, it will auto focus. If not (eg it's an AF lens) then you would have to manually focus it.
The first Nikon body up the scale that has a focus motor in the body is the D7000 but that's outside your budget.
When buying a Nikon camera body around a Nikon lens, refer to this page:
http://www.kenrockwell.com/...y-lens.htm
Find out what version Nikkor 50mm lens you have (they have made hundreds over the years; 50mm 1.4 SC, 50mm 1.8 Series E, 50mm 1.8 AF-S and so on) and then consult this site as to what bodies it can mount to and what features it will or will not have.
If the lens is auto focus, it will have all capability on any Nikon DSLR body. If it is manual focus, there are different levels of functionality it will have on different bodies.
Most used Nikon 50mm lenses sell for $100 or less though, $300 if you have a 1.4. So this is really nothing to choose a camera body over unless this is some particularly nice 50mm lens like a 50mm 1.2 AIS that is worth over $500 and you are particularly fond of.
It may be best to just buy a new something like a D3200 with its kit lens and put your 50mm (whatever version it is) up for sale to fuel you with a couple memory cards, spare battery, camera bag, etc.
I have a Nikon D3200 and it's great. I also have a 50mm Af-d lens, which means I have to focus manually, but that's no problem either. If you have the Af-G lens, it will autofocus. You can get D3200s for about $400 on ebay.