Larry, all that depends on location and each individual installer. You could find a number of installers that would charge in the $4-5 psf range, but then you could go on Craig's List and find people actively searching for work and offering installation at 50 cents psf.
I try not to get caught up too much in the "price per square foot" business. When someone asks me that question, I tell them it depends on the job, and I would have to look at it to give an accurate answer. Some jobs are gravy, some are far from it. I look at the job and price accordingly.
Asking that question is like asking, "How much does a car cost?" or "How much does a house cost?".
