I recently just had my tinting professionaly done. I have no regrets about spending the extra money on having them do it. It cost me $200 ($180 for Passenger, Driver, Rear, and two quarter windows - $20 for a sunstrip on the windshield). Like most of the others have said, this is somewhere where you probably want to let the pros do it. It had never crossed my mind to do it myself due to all the terrible (and I do mean terrible) jobs I have seen around by people doing it themselves. Also at most respectable shops you get a guarantee of no bubbling, no peeling, and no fading/discoloration, so you're pretty much worry free. It'd be quite the other case if you did it yourself.
Just remember most shops have computerized cutters, the correct tools and materials, and most of all the experience.