I'll let you know what our bid is going to be because I'm going through the same process. I'm adding a 2 car garage and a second story addition on top attached to our existing 3 bedroom home on 1/2 acre. We were trying to sell for about a year with no bids in this dead California market so we decided to stay and do an addition.

I'm at the beginning of the process now but hope I don't end up with your troubles. California is particularly hard hit in the housing market as well as the contractors who are out of work as a result.

BTW my budget is $100,000 for 620 square feet and half that is a garage which does not require much fit and finish. Keep in mind I live in the Bay Area of California where things cost more than average.