A great keyboard like the Motif and your only willing to spend $150? Ok, but that axe sure deserves something better and at least twice as much. I guess you go Behringer shopping...

this is only for my room, so I don't need it to produce that much volume. I just want something that has some good sound and isn't too expensive, since I can use other speakers for performances.

How about an old Pioneer och Technics HiFi? Should be able to find those in any decent red cross/charity/second hand-store. Personally I have never felt the need for a separate keyboard amp [at home], my Creek stereo works wonders!

Stay tuned a few more weeks. Alesis is about to start shipping a few products, one of which is at least one keyboard combo amp likely to be more in your price range.