A lot of people have varying opinions on spray tint. If you mess the up it will take much more work to clean the tint off if they are sprayed. The film is cheap and will probably give you a lot less trouble.
In my opinion i would not use spray on window tint. After awhile it will start scraping off of the window. Another problem with it if you are thinking of a black tint it will most likely turn to a purplish shade.
In order not to waste time and effort bring it to a proper installer. I am afraid the problem will show later if tint is not properly installed. It needs accurate cutting to the edge. It needs proper coating. Tint films bubbles. And besides installation will not cost you so much.