Sure, most any electrician can sell/install a generator and transfer switch, but then who services the unit on an annual basis and more importantly, if the unit has trouble? I used Powers Generator Service for this very reason. They service the unit every year (change engine oil, etc), but also offer 24/7/365 service should anything go wrong. Imagine if a bad storm hits and the power goes out for days...but your generator decides to crap out during this event. I purposely chose a company that would both sell and service the unit for this very reason. I'm had my 25KW Kohler unit for 6 years now and have had to rely on it several times when the power from that lousy NHEC goes out!
http://www.powersgenerator.com/
Good luck!