IMHO, if trading, each person pays postage one way. If sending blanks, you pay postage both ways. For most current or recent shows, the seed usually provides a DAT tape, and therefore it's a good idea for the root to have DAT capabilities as well, thus enabling most people to get high quality, low-generation analogs. There is no payment for this service, ever. Don't do business with anyone who wants payment for taping.
Most heads are only too happy to make copies for anyone who asks.
Deadheads are audiophiles. You want the best possible quality tape you can get for a free recording. You will reduce the quality of the tape, for the person you are making it for and any copies they will make. Always make the best quality tapes you can with the equipment you have on hand. This information is needed so that when the administrator sets up the tree everyone gets the best possible recording they can get, no matter what type of equipment you may have.