Same here. I've sent out many seeds over the years but there's always a real but not my return address on the package and I politely decline any reimbursement whether seeds, cash or what have you. There are maybe 4 or 5 people I've met in pot forums in 11 years that I know and trust to swap back and forth.
I've been pollen chucking for 20 years so have lots of beans. Should be popping out fem seeds of many decent strains before too long and looking forward to sharing some of those.
All I've ever asked in return, is that when they can, they pay it forward.