If you're making a portable you probably need something to watch it on. (Unless you want to guess what's happening in the game, but I wouldn't advise that) Anyway, this forum is your "Hacking a pocket TV/screen" one-stop solution. Share your experiences and knowledge here.
http://myworld.ebay.com/koosshop/
Check him out! You might have to search his products to find one, though!
I personally boutght one, and last time I checked there were like, elven in stock. If he runs out you could ask to restock, I guess.
EDIT: Actually I'm starting to question myself if the screen I bought will work for portables. I really hope its battery operated and not required to be plugged into a car.