If the CBRE agent is a transaction specialist or a transaction manager, it is likely he/she is not a licensed real estate agent in the state where your post office is located. So, after doing your homework to discover the fair market value of your building and knowing what rent you are willing to accept, consider offering a reasonable transaction fee in lieu of a commission since only a licensed real estate agent can charge a commission. If you have any questions, please contact AUSPL headquarters at 800-572-9483.