Originally Posted by roztom
...should I go to a big box and get a low cost one from there and have them install it? Is that the best overall economic choice for product and installation? ...
NO! Never do that. Alot of the installers that work for the Big Box Stores are only concerned about "rapid" installations. Some should not even be doing such installs, and worst of all, you are going to pay alot more than you would, were you to hire a local contractor to do the job.
Don't hire a "jack of all trades" for such a job. I have seen so many horrible exterior door installations, performed by ...."a guy that I hired who does home improvement work and repairs..."
Take Bob's advice regarding a local, reputable contractor with experience on installing doors.