I just got prices from two shops in my area for window tint. One shop uses 3M and charges $235. The other shop uses Solar gard and charges $185. I realize that some of the price difference could be just in the difference of the shops and they both have nationwide lifetime warrenties. Does anyone know about the differences between these tints and can make a recommendation based on the prices? I know some people that have the solar gard and are satisfied with the shop's work, but I do not know anyone that has used the other shop.