If he lives in Maryland you have to go through an FFL there. Federal law says no interstate sales except via FFL. You can take it with you to the FFL in Md and do the transfer. Just make sure ahead of timethe FFL is OK with accepting a firearm from a non-FFL.
It's not the money thing, it's the interstate commerce - which hasn't meant selling in decades. It simply means stuff moving across a state line.
Don't put yourself and your friend in jeopardy of jail time.