Must use agent to sell home in order to buy new?

My husband and I are purchasing a home (UT). It is in a planned subdivision with lots being sold from two different builders. We have been approved for our loan with flying colors. We have been working for two weeks with the builder whose plan we most liked. He just informed us that as well as our $500 down to hold our lot, we must use a real estate agent to sell our existing home, or they will not hold a lot for us. Can they do this?

[HomeGuru]

Yes. The builder cannot depend on homeowners inexperienced in real estate to sell their own homes. The builder must depend on experienced professionals.