But even though grossly overpriced ($4.50 for two pieces of cardboard?), they were generally not available in the brick-and-mortar establishments; they had to be ordered, at ridiculous shipping charges

With free shipping, they worked out to about a dollar apiece

I bought 6 baby blue ones as an "add on item" for only 98c each, free prime shipping, gotta love Amazon!

Very nice quality with quick free shipping.

I find that amazon has one of the best prices for these with fast shipping, so that really nice