You can actually get them as small as 5", but at a large price. The best website is probably
www.earthlcd.com. You can also get a NTSC screens that are mostly made to be used in cars with VCRs, and then put a touch overlay on that. The drawbacks with NTSC (otherwise an RCA connector) is that it has very bad graphics, and you probably wont be able to read text on it.