Yeah, they aren't cheap.
A good one on eBay should be around half that, but I dunno how GBPs work.
The steel plug should be near the water pump, but I'm not sure the 250 has one. I'm pretty sure it's a Zilla thing. Tell him to take off the impeller bolt (it's left hand threads though! Righty loosy lefty tighty!) and have a look under there.