I'm probably going to get a smackdown for this but why would anyone search for a 'cheap' tint? If price is a concern, sell your car and buy a bicycle. Shop for your shoes at Wal-Mart.
A 'GOOD' tint is not going to be cheap. There are good and bad films out there, some of the better ones are 3M, Llumar, Huper Optik. Those tints cost anywhere from $300-$600 for a 40"X100' roll. It should take about 2 hours to install. The Installer 'should' have a indoor location to install from, have insurance and lots of references.
A cheap tinter will not know the name of the product that he's installing. He'll have no references and probably no insurance on his Toyota Corolla when he pulls up to your house to install it in your driveway.
I was always told that a cheap man always pays twice. Once to get it done, a second time to get it done right.
So before you start shopping for cheap tint, go out and shop for good references.