Just got through DEMCI basic 360 fan one
Looked at them but thought the frame too thick to sit between the top panel and rad. In the end I went with My basket at Overclockers UK:
Total: £22.37 (includes shipping: £6.02)
There is more leeway on the other positions but I was starting with the intake to see how restrictive it still is before I discard any more of the supplied filters.