if you have glassware, you can get a glassjack (pointy piece of coloured glass) that looks better than a metal screen and is better than nothing. however, its a pain to keep, cuz it falls out with the ash usually
You should specify whether or not this is for a metal pipe or a glass bowl. You can get glass bowl screens at a headshop if you want, but you don't need it. In fact I've never used one with my glass bowls. But you pretty much always need one with metal pipes. And they are cheap.. Or free, or at least I used to get them for free at headshops.
I beg to differ... Ive never used a screen with my metal pipe (Yes i realize you said ALMOST always) and if you cant find a screen just use a stem or small peice of nug to block the bottom cuz once they burn its sucked in with the ashes and disposable.
Hmmm I hate metal pipes anyway and screens usually come highly recommended for them so i just always obliged. But to each his own.