One way I've done it is to make a website for the event using wordpress, install the PMPro (memberships) plugin and a plugin that allows pages to be hidden (can't remember the name off hand). Then, you would make a page that has the embedded stream prefereably with the steam link restricted to the page url. Then create membership levels and set the price which gives access to the stream page. This is a pretty bad explanation but here's where I did that:

www.aerialdragonslive.com

If you try to go to one of the stream or replay pages, it will ask you to register and that's where you can see the different membership 'levels' that give access to the specific streaming/replay pages.


The other way is if your stream host allows PPV, like boxcast.com
I have a boxcast account with PPV and 1080p60 capability and if you want to utilize that I don't mind getting you set up as a temporary host. Of course I'd have to take a cut but if you're interested just let me know.