Heres a good solution, the PoGa kit.

http://shop.4dsystems.com.au/poga-portable-gaming-console/289-poga....

I recently got an email from 4dsystems, since I get some rare updates from then and found this.

Its a complete kit to create a full hand held with pretty good graphic and sound capabalities for just 50.

Consider if you don't need a screen and convert it into a console it could be much cheaper without the Screen.

That and they give discounts in bulk, so maybe its something to look into, since overtime it could cost less to build such a system.  Its not quite $10-15 which would be more ideal, but its pretty nice.