I'll second the vote for the Vivitar VHE. I have one of these in 135 mm, f/5.6. It's a sheer joy to work with on my D2; covers 4x5 easily, no sign in the prints of any light falloff, and also does an excellent job with 6x9 and 6x6 prints (though I'm now doing my 6x6 with an 80 mm f/3.5 Anastar that came without the Kodak Reflex II it was originally built onto). Heck, I'd use it for 35 mm if the enlarger column were tall enough and I could reach to focus; it's a better lens than my El Omegar 50 mm f/4.

I got this lens with my D2, along with a bunch of boards, cones, plates, negative carriers, and a Zone VI cold light, for $250 -- which, by my calculation, means I got the lens itself for about 85 cents...