LIFTKIT IS FREE AND OPEN SOURCE. The website's just out of date.
https://github.com/Chainlift/liftkit
Most of the feedback folks are providing here was raised about 6 months ago on Reddit and is actively being worked on. You can check it out here: https://www.reddit.com/r/webdev/comments/1m41arx/i_spent_18_...
KNOWN ISSUES INCLUDE: - Docs are a nightmare, screenshots are ridiculous instead of real components - Components are inaccessible spaghetti
CURRENT PRIORITIES: - Rebuilding with radix primitives - Improving docs
TO LEARN MORE: - This youtube video explains the gist of the system (though it's also a little outdated) https://www.youtube.com/watch?v=r1DANFZYJDw
I'll reply to folks as best I can.