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.
I got mine for $40 at Gametrader. I got lucky... my brother let me buy it on his birthday 'cause I was like, "OMG, I FINALLY FOUND A SONY PSONE SCREEN!"