I have not seen an NVR contract in years, howver, they used to be quite onerous if you chose another lender besides the NVR mortgage group. I worked with many folks after they signed the contract, and the loss of discounts and upgrades, closing costs, etc, made switching very problematic. However, if folks worked with me before signing the purchase contract, we were able to still negotiate many of these items.
I chuckled at the 50 dollars a month differential, many times we were talking 100's a month. Caveat Emptor!
Happy to help with a competing quote. Jim, HSOA, 703 615 4675.