Yeah that's about right for installation costs. I'm lucky, my parents do a lot of work with vinyl so they have experience putting it on. Didn't cost me a dime and turned out great.
Like the other members said, do on it a good day, use water mixed with a little soap, and have a buddy help you out. Also if you have a big enough garage to do it in, I would suggest doing it in there. It helps not having to worry about random elements outside.
Above all be patient and take your time.
Edit: Didn't see the part about you not having a garage, but don't worry about it. As 6er said, heat isn't needed. Only time we used it was to smooth the vinyl around corners/edges and to work out bubbles.
2013 Focus ST2: Oxford White
Mods: HID Retrofit, Tuned, Steeda Short Shifter Bracket, More to come...
ST2 Build Thread