If you want to save money try a local truck service center. If they sell CAT or Fleetguard filters they can order what you need. Most will give some discount to you.
Having worked for both companies at one point in my career I can tell you that there is a difference in filters. Not that I don't support my local NAPA parts store, but their filters (or WIX) are not up the same standards as the OEM parts.
I don't work for any OEM anymore, but I still buy OEM parts. There is a difference.