I just got a quote for installing a NEMA 14-50 in my garage. My garage is not insulated so there is no fishing of wire needed. The outlet location is on the wall opposite from the panel; about 20 feet across. This includes installing a new breaker in my panel for this outlet.
Materials: $236.30
2 hours labor: $136 < this is discounted labor using an Angie's List coupon
Sales Tax: $22.45 (9.5%)
Total: $394.75
I am in the Seattle area.
An important note: I have a 200 amp panel and I was worried that I needed to upgrade my panel, but I did not need to. I was lucky because both my clothes dryer and stove are gas powered. If I had needed to upgrade my panel, it will require me to upgrade my service with my power company and they said I had to cover the costs of the upgrade including external supply panel and transformer. Fortunately, I did not need to find out how much that would cost. I found this out after I called my power company and they sent someone out to confirm what they can support. This part was free. I am guessing that the panel upgrade would be thousands of dollars. That would be painful.