What I refer to is tape trading. As we are aware, you cannot legally record an officially released compact disc or cassette on to a blank cassette. A person may record a concert and keep it for their personal use, they may distribute it, but they may not sell it legally. Big companies work their way around this by bring their tapes to Italy and producing compact discs there. When brought back to the United States, or another country, they can be sold or copied as much as they please.
Soundboards are the alternative.
Bootleg companies purchase these, because of the superior near-studio quality sound. This method tends to pick up more of the music, and less of the audience. Send the tapes out the same day as the other guy. Use a padded envelope. Do not include a tape case or J-Card.