Theme isn't really a concern for me but as long as a concept is interesting I will consider it.
Sketches go for $10, though will be more detailed than shown above (construction lines will still be visible, but linework will be solid). I can do a few of these per day.
Portraits will go for $20 and I can complete them at a rate of one per day.
Character sheets will vary according to character detail, the base cost will be $60 for front and back and a few detail shots.
You may keep a commission "secret" (it will never be posted online or distributed) for a 20% fee.
You may opt for more than one character in sketches and portraits/pinups but due to the difficulty of positioning multiple characters, it counts as additional slots (2 characters colored would be $40, 3 for $60...)
I take paypal, dwolla, and bitcoin. Payment is not requested until the sketch is completed, but sketches must be paid for up front.