I had promised myself, a while ago, to clean up the air in my castleHHHHHHhouse by changing the air filter monthly. Procrastination ensued, mostly because I didn't know the size of the filter. Finally, on the 23rd, I found the roundtuit for this particular task. I was totally grossed out by the state of the existing filter (and keep in mind how much I work with animals; I am not lightly grossed out). Ew! I measured it, then hauled it outside before it could unload any (more) of its huge collection of house dust and other forms of nastiness into my allergic self.
Size determined, I rang up OSH to see if they had it in stock, and how vast a supply of $$$ I would have to hand over in order to pick up, I don't know, six of 'em. So the friendly voice on the other end of the line goes away for a bit, then returns. "14x24 is the closest I have to that size, and they're 59 cents each."
Fifty-nine cents? I don't know what I was expecting, exactly, but at least a couple orders of magnitude spendier than that. I bought 12. :-)