I don't have a perfect answer for you.
You asked for a (1) 10 inch (2) Touch Screen that is (3) Cheap.
I can get you two of those.
For a 10 inch LCD, I'd use a converter to get VGA output then wire in a standard LCD to it. http://arduino.cc/playground/Main/InterfacingWithHardware#Video http://www.4dsystems.com.au/prod.php?id=131 http://www.4dsystems.com.au/prod.php?id=149
I guess you could try to code for an USB interface to a 10 inch touch panel...I've never done it. 10 inch touch panels are available. http://www.dealextreme.com/p/touch-screen-digitizer-for-asus-10-eee-pc-1000-umpc-laptops-19654?item=6
You can get a 5 inch touch screen, compatible with Arduinos, for about $66: http://www.emartee.com/product/42176/TFT%205%22%20800
I"m sorry I can't offer a $66 plug-and-go 10 inch touch screen with ready-to-run examples.