When they pay you recived for lewd mod 1 wasnt enough the normal thing to do is raise the price, not break the game up into pieces. Especially since lewd mod 1 promised all future updates to buyers. At best its false advertisement and at worst bait and switch.
I run a small construction company and if i take on a job too cheap (have happened once) i have to eat the loss, i cant lock up 2 rooms and demand payment to give them access.
And while i agree $5 is a good price for the current content thats what should have been charged for lewd mod 1, maybe even $10 so you can continue the work.