Escrow Fee Charged By Broker for Holding Earnest Money?

We recently went under LOI for a business acquisition where we offered a small amount in earnest money for exclusivity. The broker is saying we will need to pay them a $300 escrow fee to hold our deposit. Is this normal? I come from the real estate world and have never heard of charging to hold someone's deposit. I'm familiar with escrow accounts and the nuances that come with them. I feel like that should be a part of the cost of being a business broker, no?