Seems you're not alone in wanting a filter for that 230mm monster. I did find
THIS on FrozenCPU. It's a 250mm filter that mounts magnetically.
what im worried about with these filters is the amount of air thats not going to flow through

or maybe these fans dont have enough intake/exhaust power to be choked by the filters
either way i need alot of filters and alot of materials ^^
the front part of the case has a grill outside the fan which would need a long mesh strip, i got the side panel thats about 1ftx1ft and i got the top and bottom and back where the exhaust is :S this might not be cheap lol
edit - lol didnt even see it was 17.99 ^^ looks like the h100 cost me 130(because i overpaed in store no patience for shipping ) and the filters are going to run about 100 lmao