That's a good point. Well there are a couple programs that do what mine does, but it is not something that he would use to make money. He wants the program customized so that his employees can't use it without knowing a password.
It's less about how much it costs you to make the change, it's the benefit the user is gonna get via buying your software. Do a little more research on how much it would cost him if he goes to an alternative and decide from there.
If all of the employees at 22 locations save 5 minutes a day on password entry that's really not required from a security standpoint (not to mention training time for new employees) then your customer will use your program to make a substantial amount of money.