Just bought a GEM GK360. I'm really impressed with the sound even that this model is 'low end'. Sounds better then my Roland EM-25 to be honest. Also a plus is the separate aux out plug vs the headphones plug what shuts off the speakers in the keyboard. They are hard to find these days and when they show up everyone wants a fortune for them even in defective state.
Roland G-800, Roland Ds-61, Yamaha MX49, GEM GK360, Ensoniq KT-76, Yamaha PSR-423, Casio WK-200, Roland EM-25, Yamaha PSR-410.