I actually agree with your reasoning. I didn't know that you would need to pay the full price again. Or even necessary to pay again since as you said, you already purchased it once. i will try to look around to find similar issues and maybe find a solution. The worst scenario i just create a new buyable option with the final price so no one need to buy it at full price again. You can also try to contract Itch if you want. I write again if I find something useful.