Once in a blue moon, you might chance on a Music Reference RM5 for that price. The phono section is very fine for MM cartridges in my experience. Roger Modjeski says it should be ok for cartidges with .5 mv output and more. Having once owned the Adcom you mentioned, I can say I was not very impressed with it. You also occasionally come across Counterpoint and Classe preamps for that price. They also have good phono sections. Another sleeper to keep your eyes out for would be any of the older Muse preamps with phono sections, also excellent.
Vintage preamps with stellar phono section.....
Any vintage preamps with very good phono amps in the <$500 range? SOny ES? Adcom 565? thanks...