The Subaru item is a Bosch sensor, but Subaru/IM have not released or allowed the OE item to be sold through the trade.
However, there is a Bosch equivelant for about £68. The only diffierence is I think you have to fit the OE connector to it.
I've run £30 universals without issue. I think these only fail on the models where the lambda is in the header due to the extra heat absorbed.
I currently run an OE WRX unit in the header and a wideband in the downpipe.
The OE in the header is even more expensive due to having a longer loom.
IIRC they are about £330...but got mine off Ebay (new-unused-unwanted) for about £20, and still in the Subaru/Graham Goode Racing box
http://www.grahamgoode.com/subaru/parts ... tem=GGS822