You can buy these and you can play without being instant banned. The keys are not tied to accounts, they are tied to emails, which you can change in the forums section. However, if you find someone selling more than 1 or 2 invites, you will likely get perma banned. I bought a beta invite for 130$ on another site and was banned after a single week. It turns out, the guy I bought from also sold like 20 more. He registered like 300 emails and got like 20 invites. Be careful.