Are you familiar with metafilter.com and their moderation model?

They charge a one time $5 membership to join, and it's heavily moderated, and they don't tolerate trolls or jerks very long before banning them and returning their money. They're a small scale site, and have a handful of moderators, but requiring someone to lay out actual cash to post seems to deter a lot of the behavior you see at reddit where anybody can create as many sockpuppets as they want with no problem.