I agree that professionals will do a much better job. I've seen some horrible tints that people had put on themselves.
I got quoted $200 for tint ($160 for 4 windows and rear windshield+$20 cause it's illegal+$20 for the front strip)... but when I went to pick my car up, there was a different guy at the desk. He was like "$170". I was like "OK Thanks!" and got the hell out of there before they realized their mistake.
MMM... darkness...