Some folks on this site have an Aikido tube pre and a Bent Tap-X both in your budget
EDIT: No affiliation with either sale. The Bent unit I've heard in a Class D (ICE amp) setup, and it was great.
I've had a tube pre/Class D setup, which I liked a lot. Never heard the Aikido unit, but it has a good reputation. I can only imagine the 6SN7 would give a big, juicy sound.