You can pay the full price, or the going rate, now. It is free. It always had been. Both the older, "stable" version with all the content and the newer, "preview" version of what is still being worked on are free directly from the developer. Should there ever come a day that Dark Cookie is done with it and calls it "finished," he has already said he'll have considered it paid for. Retail price would be the lowest he could offer it on a site such as Steam.
However, don't hold your breath for that day... He wants to add 100, 200+ more characters.
See, that is the key problem with this format of development. You imply it might never be finished, and that is all well, and good BUT it doesnt lead to long term followers, money, and a finished product. I understand the desire to make one's Magnum Opus, as I have been caught in that trap myself a few times, which is why I "complained, griped, your choice" here. IMNTBHO I was just voicing a bit of disappointment in the rework of an unfinished product that could have been finished. The term KISS is used because it works. Lord help us if Grisaia went this route; we would never have seen the first 30 hour VN, and I know that this is a slightly different game, but gamers are a fickle clan, and I consider myself a pretty standard, if old school, gamer. That's why I say I will gladly check out the completed product when it comes out, and pay the developer for the chance to do it because a person's work deserves to be compensated, and my wallet opens for a good dev because I want to see them do more. Another question is what if there is a new upgrade or whiz-bang system that comes along, and DC wants to incorporate that into the mix so he decides to start over again? I mean we are apparently already feeling the effects of this when old saves are borked within an update or two. Gamers will lose, and probably already have lost, interest in the game, and that is pretty sad because it was a good game.