I can't with a good conscience recommend paying $20, $60, or $100 for early access to test Landmark's closed beta.
After more than a year of testing, Landmark is still nothing more than a handful of loosely connected game systems. The pace of updates has slowed to a crawl in the last six months. Countless milestones have been missed, and some key priorites have dropped off the roadmap entirely. When there have been updates, they've mostly been to add new textures or props for testers to build structures for Daybreak's other upcoming MMO, EverQuest Next.
If you're curious about the MMO development process in a struggling (but still optimistic) triple-A studio, you might enjoy testing Landmark. The developers, artists, and producers actually test alongside players, and they do value our feedback and occasionally make changes based on it.
Landmark does have a lot of potential, but I wouldn't even call it a "game" yet because it simply isn't very entertaining. I'd generally recommend most players wait until Landmark reaches open beta (free access) to check it out.