Try contacting the guy in the link below (dabbernz) through eBay - he sells quite a few UNI MR175 filters (p/n NU 4026), as UNI Australia still makes them. Sometimes he may be out of stock for a bit, but he always seems to get more, and IIRC shipping time is 10-14 days. These are really nice filters with a foam sealing strip added around the bottom, in case the airbox foam gasket is in bad shape or missing (as it usually is). Apparently he can also get the filter frames.
http://www.ebay.com/itm/Honda-MR175-197 ... ee&vxp=mtrI'm not sure what type of adhesive they use on filter foam, but if applied correctly it's really durable - maybe something like weatherstripping or plastic cement? Some of them seem to have heat-welded seams as well.
Ray