just bought one at oehq.com

based in st. louis.

easy menu to order parts.

motorcraft # for the little air filter is FP-51. Cost is 16.03
while you're at it you ought to get your engine air filter, too.
motorcraft # for the engine filter is FA-1772. Cost is 27.74
They ship UPS.

very easy to change the little filter, it's about the size of a canadian pack of cigarettes, and costs close to same.
just pop off the outer cover, squeeze gently one of the tabs holding the inner cover on, take that away and you then can slide out the little (very dirty) filter.

as you can see by a previous post dealer charges double, you'll have to wait a couple days no matter what.