That's the purge valve for the charcoal canister (although, as other posts have stated, for some reason Toyota calls it the "bi-metallic switching valve") -- lets air through once the coolant gets to a certain temperature, no air through when it's colder. OEM part number 90925-05068 . $80 is obscene -- MSRP is roughly $40 (just bought one from my stealership in the last month, and they always charge list, no more, no less). Should be able to find aftermarket for $20 or less...just search for the OEM part number.
If you're feeling lucky, there's a guy on fleabay selling junkyard pulls for pretty cheap (for some reason, he has them listed as a BVSV, which is a different vacuum switch). I wouldn't really recommend a junkyard pull for this part, 'tho -- the plastic gets really brittle after a while.