I'm not too keen on hosting private "RTB Premium" servers. I don't think how much money you're willing to pay should define who you get to play with.
As for payment options - I think I'll go with PayPal and Amazon as the two options. I will also accept the delivery of live farm animals as payment if PayPal or Amazon are not possible.
I'd rent a dedicated server if a trusted source like RTB were offering it. There are currently few servers of merit with consistent uptime and dutiful moderation. It is already possible for most people to host their own servers, thanks to recent updates made to BL, so offering such a service wouldn't encroach upon number and/or variety of servers available to players. If anything, a player consistently paying for a dedicated server is more likely to maintain and be active in it, as are the players who can then come to rely on the server being online and their creations being ever visible to other players.
If you created a simple way to setup a paid, dedicated server through RTB, I'd be in line for renting one. Your experience and resources in relation to the RTB service make you the ideal person to setup such a service. "Owners" could choose from the add-ons already being hosted by RTB, and presumably all of the other server options would be available as well.
The idea has merit, and I believe it is worth a second thought.