Do you have a Roland Keyboard?
It really doesn't matter.... Any major manufacturers keyboard amp will sound great.
Here's a short list:
Fender, Roland, Peavey, Yamaha....
Also consider a small PA system from any of these companys. You can often find a used 4 channel powered mixer/Amp with two 10" or 12"
speakers at a local music store for $250 to $300. This is going to blow away any small combo amp, and you have the advantage of running a piano, synthesizer, organ, or drum machine and a microphone all into the mixer and setting up your levels.
Dom Franco