. . . I don't think i looked for aftermarket filters on ebay last time so i probably didn't notice those ones. i know that there are only so many manufacturers of filters out there, and many are the same with just different badges, but i'm always a little leery of filters. over the years i've seen some aftermarket filters that were just plan cheesy feeling and looking that didn't even have a cost savings over an oem. years back i did an oil change on a porsche and there was no nearby dealer so i ended up getting a fram from a local parts store. it had the feeling of an empty beer can and cost $14. the next time i went by a dealership i went in and bought an oem filter for $8 and change. that filter had the feel of a full can - i'm guessing a spring and check ball and probably all around better quality for nearly half the price.
i'm sure most all aftermarket ones made today are good, but after a $2000+ injector replacement on the duramax a couple years ago, i'm pretty cautious about what goes in the system.
I understand your concerns for quality. I feel the same way. You can obviously tell the cheap junk from the better stuff. I buy OEM,
if they are reasonably priced. If not, I try to find a "quality" aftermarket replacement. The farm tractors get OEM. Once a year oil change just doesn't warrant searching for a cheap substitute.

My Ford trucks get OEM, because they are readily available at wallyworld and A-zone. The Kenworth gets Fleetguard or Luber-Finer. The CAT filters are just priced too high, and the NAPA filters are almost as expensive as the Caterpillar. Example: the air filter for my KW in a Fleetguard or Luber-Finer cost about $50. Same filter from CAT cost about $110. Same filter from NAPA is about $100. I used to buy a bunch of my filters from NAPA, but now, they've gone crazy with the prices. And, really, that's too bad. The NAPA (WIX) filters are good quality. I like them, but I won't pay double price for them.
That said, there are only a handfull of filter manufacturers. All of the "brand name" filters are made in just a few factories. I would love to see a full breakdown of who makes what, but here are the major manufacturers that I'm aware of:
Champion - manufactures the OEM for MOPAR and VW (some sources say they make the AC/Delco too); aftermarket brands of K&N, STP, Deutsch, Mobil, Royal Purple, etc; Champ (choice of many quick lube shops); and Luber-Finer (heavy duty truck and equipment filters)
Cummins - manufactures OEM Cummins (and I understand Caterpillar also); aftermarket Fleetguard.
Purolator - manufactures the OEM Motorcraft and Bosch; aftermarket brands Purolator One and Purolator Plus and some of the Quaker State filters.
Honeywell - manufactures aftermarket Fram, Pennzoil, and the rest of the Quaker State.
Dana - manufactures aftermarket WIX, NAPA and Carquest
Baldwin/Hastings
Donaldson
This is not all inclusive. This is just what I was able to find and verify. I still don't know, for instance, who makes the OEM filters for JD or NH, but I'll bet that it's one of the "big boys" listed above.