It’s tough to be green when you have a Renewaire ERV and the flimsy filters cost $48/3 pairs. I just found a source on eBay with 90′ rolls of MERV 8 spun polyester for $75. Each filter for the EV200 is 10½” x 22¾”. Three pairs cost $4.58 when you buy in bulk and cut it yourself.
http://www.ebay.com/itm/Air-Handler-90-ft-x-24-Filter-Media-Roll-MERV-8-2JRV7/132112827490

Have you found any other solutions?