1. Your price should include what you pay. Shipping to an individual's FFL should be covered by the customer.
2. Never let a gun go without having the money in your hand. You are then paid. If the customer fails the background check, chances are slim that you will get them to pay a restocking fee or return shipping. So as long as you have your money, the firearm is at the receiving FFL, the individual is out of the cost of a firearm, not you. But your part is done.
"A well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed."
Life Member NRA
Life Member NAHC
Former President of the ECPT (Eifel Combat Pistol Team)