Build a multi-tier registration system with support for multiple payment gateways

I am trying to build a multi-tier registration system that assigns users to a role depending on the tier they've signed up with.

For example, when they signup (with payment) with Gold plan they will be assigned the role named "Gold user".

I can then use the role type to show appropriate sections within the admin panel.

Is there something existing that is close so I can further modify them according to my needs?