£150 sounds dirt cheap. Where'd you get quoted that?
I've read of some real horror stories with tinting peeling and bubbling after a short time.
Thats how much i paid over a year ago, southampton monsterwraps, they also did my mk4 3 dr £99 on a special offer they do occasionally.
I had my chrome window trims done at the same time so possible they offset a small discount as I use them on every car.