Is this the "Bi-metal Vacuum Switching Valve (BVSV)"? Look on
AutoZone's free repair guide:

http://www.autozone.com/az/cds/en_us/0900823d/80/13/ea/d0/0900823d8013ead0/repai
rInfoPages.htm

This particular one is for the evaporative system. Ask whoever told
you which one. The BVSV vents fuel vapors from the tank into the
intake manifold instead of allowing it to vent to the atmosphere.

Call up the dealer and ask for a quote. There are online Toyota
dealers that sell at a discount. Now if the part number is
25870-74090, you can get an AIRTEX Part # 2F1032 from rockauto.com for
$62.79+shipping.