I run premounted 24mm Take-Off 22s front and rear. My LHS sells them for about $30/4.
A little sauce, and they stick real good. They wear pretty quick tho. The nxext harder compound is CS27, which is nearly as grippy.
A lot of guys swear by the Sorex compounds, but it's a bit more since they're abotu $35/4 for just the tires. Add inserts and rims and it makes more financial sense (to me) to go with the Take Offs.
-dave