Landmark, you've got to drop some cash first. That's just the way it is. But the good news -- aside from the fact that buying test access also involves owning the game when it launches for real -- is that you can get away with dropping substantially less cash for a little while longer. Landmark is on Steam as an early access title, and it's currently having a sale that shaves 66% off of every founder's pack available right now.
Due to the sale, prices range from $6.79 for the lowest tier to $33.99 for the highest. Already bought one of the entry packs? You can also pick up an upgrade for your founder's pack at a similar discount, so if you bought the lowest tier a while back you can upgrade to the top for a cool $27.20. Act fast, though; this sale is only running for a little while longer.
[Thanks to Christian for the tip!]