Ah yes - that's the episode, thanks, Jon.

One problem here - and, I suspect, in many other places - is that buying single items (or even a small quantity of some things) isn't easy because of packaging. Want one of a particular type of screw? Too bad - you have to buy the smallest pre-packaged quantity, which is 25 - but what do you do with the rest? You can't bring yourself to throw them out because you paid good money for them and anyway you might need them one day, so you keep them.....and next time you need one screw you can't remember where you put them, so you buy another pack......