Just wondering If it would be cheaper to buy a In-Dash LCD and then add a USB touch screen overlay to it or would buying a in-dash unit with touch screen already on it be cheaper? In-dash screens with touch screen are still rather costly and wonderred if there's a more cost effective solution to those who want touch screen but Have a normal screen. I know you can get 7" touch screen kits but are they worth getting? Are they any good?

Thanks.