Most people will have found someone that does a good job, both in
pricing and service and stick with them.

Maybe talk to your friends, good service is good service.

Failing that, get quotes from several retailers/installers in your
area. Installers work for the retailers.

By talking with the salesmen and asking their opinions you'll get a
sense for who wants you to be happy and who wants you to pay as much
as you can afford.

If they really want you to be satisfied they will only hire good
installers.

I've had the best experience with people who have been in the business
for generations. Good personal customer service means more to them it
seems.

You shouldn't need to pay for quotes - they should want your
business.

Let them know you're getting several estimates, the good ones will
respect you and you will be less BS'd by the others.