On Board amp and a speaker.

I built a cigar box ukulele last winter. It is a real dud in the sound department. It really needs some sort of amplification. So I want to amplify it, but I would like to put the whole thing in the box and put a little 2" or 3" speaker in it and battery power it. Can that be done? I think it can be done. I would appreciate any advise from anyone who has experience doing this. Keep in mind however that simplicity is always the thing for me. If it is too complicated or too expensive I'll just leave it a conversation piece and play my real ukulele. I'm not looking for the ultimate sound experience either, just sound would be nice. Thanks all.

There's a dude in Kona who makes something similar. Might be good inspiration: http://powerukes.blogspot.com.

A Danelectro Honeytone's inards would probably work, but they cost about £32, small belt amp run on a 9v battery, connected to a piezo pickup.
Or maybe use one of those headphone amps, they use a small speaker.