Pay 10 dollars a month for something I could more or less get for free on the Erlang mailing list? I don't think so.
* Free, in order to attract lots of people and get some network effects happening.
* Nor enough to compensate you for doing actual work to solve problems.
So to me it seems like neither fish nor fowl. If I want to hire a consultant to do stuff, that's one thing, and something I'd spend a lot more than 10 a month on! Free mailing lists are another. Something in between for a fairly niche topic... I'm not so hot on the idea.
It doesn't require a lot of time to share the fair amount of information I collected while writing Hardcore Erlang and the feedback makes it worthwhile, even if the money isn't.
There's a marketing sideline to this as well. A member-only mailing list is a great way to size up the market. Perhaps there's none, perhaps there's a sizable one. If I get swamped with subscriptions then I could invite other experts to help me and, perhaps, sell products or services my subscribers would be interested in.
Also, I have a number of crazy Erlang projects in mind like a Mac Cocoa bridge, trading software and others. I could dedicate myself full-time to writing code for The Erlang Journal, if the number of subscribers allows it.
In the meantime, I don't look to solve all the problems that folks bring up, I just have to solve enough problems for them to keep coming back.
There's also a public source code repo at http://github.com/wagerlabs/thinkerlang/tree/master that you may want to take a look at.