Best way to go about purchasing 500m+?

Alright, so I've played off and on for over 10 years now. I staked off 500m and quit about two years ago, but now I want to come back to the game exactly where I left off. I want to buy 500M but I don't know the best avenue. Have never bought gold.

1. I have no vouches on here and just made my account. I have a hard time believing anyone would carry out a $600+ transaction with me.
2. I don't know what gold selling sites I can trust
3. PlayerAuctions made me go through a long verification process with docusign etc. and asked me to provide my SSN, at which point I told them to shove it. My paypal is verified and tied to my bank so I don't see why they'd ask for that.

What should I do?