There should be no processing involved in this type of photography if you do your lighting right. Occasionally you will get a client who asks specifically for a known flaw (zit or something) in which case I would add a few bucks to the fee but ~$20 is about the going rate most places for this type of work and it should make a nice little return on investment.
Shoot tethered for immediate preview and printing.
Originally posted by mel Dang Mike. That many people by yourself? I'd charge more than $20 because that is going to be a huge amount of work to shoot AND process/print in the same night.