[Nabber]

I hate to break it to you, but in layman's term it's a promise to purchase a property through that realtor you signed the contract within the time frame on the agreement, it's kind of a guarantee that the realtor gets paid whether it's a for sale by owner or through a builder where there is no commission. I've never used one myself but I'm sure a lawyer (Trout???) can confirm they're binding are you're most likely on the hook for the commission agreed in the buyer brokerage agreement.

I take it the builder won't offer anything to the realtor? I'd say speak with your agent about the contract, see if you can work something out. I'd recommend getting legal advice before you sign the purchase contract through the builder, just incase you have to pay the commission.