Hi, I am interested in this project. It sounds like it would be fun to build. I have the skills to develop a TCP stream proxy and the signup part is simple. My understanding is that you already have an RTMP stream somewhere and you need a system to sit between that stream and the clients (eg VLC) to only allow paid customers to access the RTMP stream. You need the system to include the signup and payment system and the RTMP server which checks authentication. When the user is paid up, they get a unique stream URL which gives them access to the RTMP stream.
Example:
Client (VLC) <-> Your server (authentication) <-> RTMP stream
There are some details which we would need to work out such as where you will host this (eg Digital Ocean, Linode, your own server, etc) and which payment gateway will be used to accept payments (eg Stripe, PayPal, etc).
If you're interested in my bid, please send me a message.