It can be replaced with a standard Bosch style relay which you can pick up at Radio Shack. 30 amp automotive relay part number 275-226 ($6.79).
http://www.radioshack.com/product/in...ductId=2062477
In the meantime, you can give the top of the box a brisk tap with your hand. This will stop it from running.
If you'd like to go with a genuine Subaru part, the part number is 26735AA012 from the subaru dealer. It retails for $51.45.