I was told by a local 3m clear bra installer that you dont want to heat it up very much.
You simply want to get the panel warm and start to peal it off maintaining constant force where the clear bra meets the paint.
If done this way it will leave minimal glue residue behind.
I used this process on a car recently and it left no residue at all.
I think for price it completely depends on how hard it is to get off. The one i took off took me about 5 minutes. It came off in one piece. However i have heard of them coming off in pieces about the size of a dime.
