i will gladly give money to the first ATOTer who can tell me where to find o-rings...

[Jeff7]

This

surprising sometimes just how much stuff mcmaster-carr sells

Them, or a place like Mouser or Digikey - I'd like to see their warehousing operation.
Mouser has no minimum order...and it looks like Digikey removed their minimum order requirement now too. The warehouses have to be huge to house so many components, but also quite efficient to manage some of this stuff. You buy things like resistors in anything but a reel, and you're talking about maybe 20-50 cents in components for just a single item on the list. Either they've got some extensive automation, or else they pay their workers $1/hr.

 

[Old Hippie]

They are interchangeable hardware like screws and washers, have sizes and gauges and compositions,

This.

 

[marvdmartian]

Yellow pages, check under gasket. We've got a whole store here who pretty much sells gasket, o-rings, and other assorted items like that. They've done a booming business for many years now.

 

[alkemyst]

This

surprising sometimes just how much stuff mcmaster-carr sells

problem with McMaster is you usually have to buy a ton at a time.

Fastenal and any local 'supplier' level shop should have all the o-rings one would want. Usually easiest way to find them is calling around to machine shops and mechanics to see where they get there hardware from.

This is how I found a dedicated metric fastener shop here. Every length, hardness, type of head, and thread-pitch I could ever want. They sell 1 to crates. Only drawback is they take cash, check or PO only so for some that rely on credit only they are out of luck.

 

[literallyyourightnow]

You could probably snip a bit of the rubber tube from an old lighter and use it as an o ring. I had a torch and it's rings were too thin and would dry out so one time I opened up the torch and snipped 2 little slivers off the tube inside and it was still long enough to connect back to the parts inside. I popped one in at the bottom and it was perfect for awhile. It was a bit too thick so the second one I heated it up til it shrank a bit using the side of the torch tip after it had been lit. That one was still in my torch today until I was refilling it and it got lodged in there since I was too rough with it. Late but hey..