The whole process take 30 minutes, so $30 is actually a reasonable price if they can do a professional job.
I've applied it on many devices many times, and have only recently gotten good at doing it. On the MBPs, the most important thing is to not let the skin overhang the edge of the laptop (especially the screen), however slightly. It's best to let the skin recede just a hair behind the edge of the aluminum, so dirt will not get caught by skin as you open and close the MBP.
Other than that, it is a great product and really protects the MBP from scratches. I have been buying mine from Clear Protector, which offers the full body kit for $25 with free shpping (coupon code was "military", not sure if it still works), still cheaper than BSE.