homebrewing - cheapest place to get mash tun parts

i'm trying to build a mashtun out of the normal parts for homebrewing, but i am having trouble locating parts such as:
silicone gasket, stainless washer, & stainless locknut for the inside of the mashtun (to connect to the pipe nipple). the prices on amazon for some of the items are frankly out of control ($8 for a stainless washer??). am i looking for the wrong things? is there a better place to get this? home depot and goodwood hardware were both useless. there must be an alternative to an $8 stainless washer. TIA.