I wouldn't buy one of those from ebay without playing with one in real life first. When I bought my car it had a Dynavin fitted, two weeks later I took it out and put an OEM 4:3 unit back in. The Dynavin was absolutely riddled with bugs and was driving me crazy.

Maybe this one is better. Maybe it's not. There's no way I'd gamble $500 just to find out.