They do clean and prep areas, but obvioulsy they are not working in a cleanroom, so from the time they remove the plastic off the film and apply it to the window, it's possible to get dust, and it would be hard to determine which bubbles are dust and which are just water, because freshly done tints will have bubbles of water that evaporate during the 3 days that they tell you "don't lower your windows"
I would expect to pay the 220, maybe from one of the places that uses laser precut films specific to the car (I think I had gotten a quote from one of those places before and it was up around that price range)
I would think it also has to do a lot with location... here in Miami, there's like 3 stereo and tint shops on every block, which might help in getting lower prices as well.

I got a ticket for my tints once... I just removed the tint myself, went to court and the judge threw out the ticket... and then I went and got even darker tints. haha