Personally I found the best screen to be the one that suits your need and that you found by a little searching.
But...
If you need a screen monuted in a case Liliput is best for price, Xenarc for quality.
If you're going to strip the case and mount it in-dash, then the AU Optronics screen is the best so far, but MP3CAR.com store have a similar (even brighter) unit on the way so it might be worth waiting for.
For powersupply a "simple" POL PSU will do, both Carnetix and Opus have 'em.
Liliput comes with a cigarette lighter adapter, dunno if Xenarc do too or if they are any good.
/M