I need to become a lecturer. Those guys must make bank. Consider this:
A touring band: expensive and heavy equipment; roadies to move things around and set them up; special lighting; expensive and loud speakers. Ticket price, after factoring out the Rape-Me-Up-The-Pooper Ticketmaster Tax: $10-40.
A touring lecturer: just some guy; overhead projector; loudspeaker system. Ticket price after factoring out handling charges: $55-100.