Portable battery powered keyboard with GM sounds built-in

I'm looking for a portable 25 - 49 full sized key keyboard that is battery powered, has a MIDI or USB out for PC usage, headphone or line out for a mini amplified speaker, or built-in speakers, GM set or at least one piano (or other built in sound), costs as little as possible that I can use for playing, practicing, songwriting when away (and connected) to my PC.

I have searched for hours on end only to find just MIDI controllers, out of date no longer produced units, or too expensive keyboards to justify my cause.

I would even explore ideas that cover mini MIDI controllers with a pocket sized, battery powered GM sound set with an output for headphones or battery powered mini amplifier/speaker.

I have a Yamaha SHS-10 that I bought way back in the day after I sold all of my MIDI keyboard/8 bit sampling units before personal computers were affordable just for MIDI input to my new Amiga computer which came afterwards. Unfortunately it has 32 mini keys and is bolted to the wall of my newly refurbished home studio as decoration :-) .

As an example, I have a hand built a guitar with a built-in amplifier/speaker connected to a Korg PX4D battery powered amp modeller/effects:

http://i240.photobucket.c...s/YardTar/YarTar_4.jpg

(photo taken without PX4D) unit that can be taken outside the studio for practicing, songwriting, jamming, etc. and would like to duplicate that with keys which I so desire to learn and have as much fun with as I do with my YardTar.

Does anyone have any suggestions?

Thank you in advance for any help you may provide.

Go to Walmart or Radio Shack. 

Most of the keyboards they carry will do battery or AC adapter.

I have a radio shack keyboard my mom gave me a few years back. It has an adapter for AC and it also holds a bunch of D cell batteries for those "groovy" parties out in the woods. In addition, it has a bunch of sounds built in, drums, accompaniment grooves, and it even has touch sensitive keys. 

It's not a professional level stage keyboard but it sure works just fine in the studio since it has MIDI in, out, and through on it. 

I'm sure it was about $150 brand new.

If you search craigs list, and ebay (local) as well as hit a few yard sales..... check the newspaper want ads on yard sales....the sometimes list the big stuff they have and even give a phone number at times.... if so, call and ask if they have and musical stuff. You could probably pick up a working keyboard for around $50 or so at a yard sale.  I've had a few smaller ones that I simply gave away to friends who had smaller kids and wanted a musical keyboard for the kids.