Superior did a great job on my windows! I used a groupon, and yes, I paid $80 to get a darker tint. No big deal, really. It got me in their door, and I'd use them again without a groupon.
Some reviews have said they don't take credit cards.... they did yesterday, although when I specifically asked if they did the answer was "For what you're doing, yes" so it's probably a good idea to check up front to see if they will for your transaction.
It's a busy shop, and they were very professional and courteous while I waited.