By the time Uni is finished it'll be larger than a VN like Clannad, which is $45 right now on steam, The entirety of Higurashi is also $45, Dal Segno, another dating VN, which is smaller than Uni, is $40.
Currently Uni has 600,000+ words and over 100 CG Scenes and we're only around 50% done with the game.
Considering the amount of content and work that we've put into the game, I think $25 for the game is very fair.