Ive seen it done both DIY and professionally by a shop. IMO if you're looking to learn how to do it and start dipping stuff then maybe buy a kit. But if not, just get it done at a shop and be done. To get the good films you gotta know the right people and places, and if you're getting specific with a pattern the professional shop will apply it so it looks how its supposed to.
I would love to do it myself but if the diy film is junk that wont fly for me...who wants to get me hooked into where to get legit film?