Another thing to consider

if you were to start your own exchange and solicit/accept US residents, you have to acquire a money transmitter-type license in the 48 states that require a license

Having gone through that process for clients in starting up exchanges, the total hard cost between application fees and bonding requirements is approximately $75,000-85,000 before legal/accounting costs. I've seen development costs as low as $50,000 for people who know what they are doing

Thus, starting you own exchange can be a $150,000 endeavor. Compare that to the listing fees and perhaps its not so high? I dont know, judgment call..