Does the CasaTunes you have prominently on your website have an option cheaper than Sonos? On a new home I wouldn't do anything less than a Sonos Connect Amp per zone at minimum.

I'm going to do my best to create a new verb a say you're going to get Trumped here in a minute. (Trumped meaning being told the brutal truth that many people think but may not want to say out loud) You and this Builder both need to work on your branding and business plans.