95% effectiveness isn't very good compared to commercial methods. And it needs to remain wet to keep the organisms growing in it alive. It's interesting but I'm not sure that's the kind of thing Lastborn is looking for.

A couple of the new MSR models have flushable filters and are usable indefinately with proper maintenance but you'll spend over $100 on them for sure.

The only other filter I know of which fits that description are the Sawyer flushable filters...they're not cheap either by comparison to your quoted price range.