No one wants dark room equipment any more so you'll either struggle to find any new gear (yeah, Vanbar has stuff, and you'll find dribs and drabs in other shops) or it will be next to free on Evilbay or other places. I think forums like this one are a great place to buy that kind of thing.
Be very careful when buying second hand enlarging lenses in particular as many do have fungus, often due to the envirnment they're used and stored in, but often simply due to lack of use for very long periods. The Camera Market is one place you need to really watch out for that. Bring a small torch!
I think the Nikkor 50/2.8 is OK but there are better options, maybe the Schneider Componon-s lenses.