Very little usually. People often try to give them away at that size because their tanks are too small, and it's difficult and expensive to house a fish that large/growing. And it isn't an expensive or rare fish to begin with.
Absolutely if the person needs to drive to your place to pick it up. The main thing for you atm is to make sure that whoever picks it up has a large accomodation, at least several 1000 gallons, not to look for a pay off.