Been there, done that....
You get what you pay for like anything else. If your okay with spray painting a new color on your car then you will love it on your sled.
When a part is properly dipped, the actual dipping procedure is just an additional step after it is professionally painted. So with those kits, your paint is spray paint, your activator is spray paint (not ideal), and if your film is in a too humid of a climate it will bubble and wrinkle up...
Lots of variables for those to be done "right", which would be definatley not using one of those kits.
For a "Professional" look of corse. If you just want to mess around its definately fun to do!