We have a motorhome size garage door that needs new springs and one of those heavy duty openers (Genie) to match the rest. The estimate we got today was $500 for spring replacement and 800/900 for a new opener. Is this reasonable?
Definitely replace both springs at once. When one breaks it puts a lot more stress on the other one. Not sure if these are expansion springs or tortion springs. Either way it doesn't matter. If the $500 is for both springs, you are getting a real good deal. My old company (commercial door company) would not touch a spring job for under $750 (usually $1k).
When it comes to an operator, I personally do not like Genie. We have had nothing but problems when they were installed. I would go with a Liftmaster operator and on a motorhome sized garage door, I would go with the Liftmaster 3240. It comes with a Lifetime motor warranty. If the company you are using has an account with Liftmaster, their cost on the operator should be around $250.00-$300.00. Should take about an hour and a half or two hours to install.
Here is the link to the Liftmaster website on the 3240 Liftmaster (http://www.liftmaster.com/pdfdocs/114A3331.pdf)