A newhome sales contract has basically the same requirements as a resale contract. The parties intend for this Agreement to set forth the terms and conditions of a.The builder agent says it's too late now to add a realtor and I understand my mistake. Should I back out of this or continue ahead with the purchase? This is a video about the differences when you're buying real estate and specifically in the purchase and sale contract. A Purchase Agreement is a legallybinding contract to purchase a home. When it comes to filling out a real estate purchase agreement, several key players are involved: buyers, sellers, real estate agents, and attorneys. Agreement for Purchase and Sale of Real Estate (New Construction).