Sell him the software! $1000. It is 100% profit....and then tell him it is $200/hr. for any kind of support, charged lawyer style....by the minute for everything from talking on the phone to reading and replying to emails/texts. Chances are you would still have a 100% customer acceptance rate as he would have been the one to bail. :)
"When I eat, it is the food that is scared." - Ron Swanson