Hello, "{The} tiny little WIX filter for small outdoor equipment..." in my experience was a 51056 for many Kohler and other small engines.
I got a Purolater equivalent, L35310, on a jug oil special for no additional fee.
Maybe the AdvanceAuto was being generous with me? It had to be over the common allowance.
Maybe the "special" little filters are priced opportunistically? Price gouging, anyone?
Maybe they have limited runs of production?
All you can do is get the cross reference numbers and shop as you would for anything else.
The 51056 has, in addition to the Puro #, Hastings, Fram and NAPA crosses.
There's also a Baldwin # but mystery filters which seem not to exist don't count. Kira