What if you gave them a bid/estimate almost a year ago thinking they were going to build last summer and they are finally just about ready to rough in now?
I have one of those, but I know them well and the estimate was for financing reasons and was nothing set in stone. Her father is a construction guy I have worked around for many years and knows materials are not necessarily same price as a year ago either. He is happy they had their lumber purchased already before prices went up though. Just haven't gotten much done until recently.