ULib, ULX, and as far as I know, all direct Team Ulysses created projects are 100% free for non-commercial use.
There are ways to donate, and some of our team members do create scripts not directly Team Ulysses related they sell/have sold before, but, no, you can't "buy" ulx.
Who knows though.
If we were offered enough money, perhaps there would be consideration.
Almost everything has a value.