My best single one probably was a Wilson JK Staff 85 in really nice condition for $2.99. Best haul was a Prince Comp Series 110, Dunlop Max 200g, and Slazenger Silhouette all for $2.99 each on the same day at the same store! I've also found Kneissl White Star Mids, Snauwaerts of various types, a perfect Adidas Haillet, lots of Yonex frames, etc. But lately the pickings have been pretty slim.
Today's ray of sunshine came in the form of a Prince Woodie with cover in really immaculate condition, but sadly warped about 1/4" from perfect, for $2.75.