It has one tube more than your looking for, but I think the Cary SLP-50A is a real sleeper of a pre and can be found used right around that price range. Really outstanding value! SLP-50B uses the 6922 tubes (more common and popular than the 6CG7's in the SLP-50A). In my system I compared the two side by side for several weeks and swapped out all kinds of premium 6922 tubes in the "B". In the end I sold the B and kept the A. Still have it, still love it. In the ARC family, and more fitting your description, you may be able to find an LS-2B which is also a fine pre for the $. Also Quicksilver's Line Stage can be found in that range, as well as an older Audible Illusions. No long-term experience with either, but have heard and enjoyed both in various friends systems, and both have great reputations.
Marco
Marco