It is a membership model, not that uncommon.
If you read into the site you will see they are offering "Preconstruction" memberships at 50%. Earlier in the thread you will see they offered extra % off for web menbers (co-ar15.com).
They state they will return the funds if the building is not completed in a set time (this is in the contract).
While this may not be a model you want to participate in it is common for membership based clubs of many sorts including golf and country clubs.
I signed up. I'm not woried about losing the $120, I know the area and think they will do just fine. You are welcome to wait until it is built and pay the full amount.