on the block theres the temp sensor on the side near where the waterr lines for your turbo go in. there 3 wires in it with spade connectors. just unplug one at a time till the fan kicks in.
http://htarchive.org/showthread.php?t=2777724 750 dollars. works out bout 470. obv as theres not many for sale its hard to judge a price. see what everyone else thinks. i'd pay 300 - 350.