The builders contacted the sip company and they confirmed the prices. Still a large gap between the sip and standard construction.
I think were gonna do 2x6 on 24"oc with 4.5" of 2lb closed cell in the walls. Then r60 blown in cellulose in the roof.
Regardless of anything else, don’t do anything other then 16” stud spacing. The argument of better R value is BS, and it’s just too far apart.