Seriously, this looks like the one you are after:-
http://carlovincriminals.eu/Vauxhall-Omega-C.html
I am not sure if you wanted the one with integral brake light . . .
http://www.nicedeals.co.uk/product_info.php?products_id=11511

Irmscher did x2 styles.  The more common flush fit to the boot and the pedestal one, which seems to be the one you're after - like the copy that Car-nut has pasted in.

The common flush fit to the boot do become available every now and then, but a 'genuine Irmscher pedestal' one is very rare to find and can be around £150 + 2nd hand 

If you really want the one like car-nut shows I'd go for that.  But like others have said, for the price RobG's spoiler at that price is a good deal indeed

I did say "can be", doesn't mean the seller will get it though.  As some things are only worth what someone want's to pay for it  .  Its true to say that  just because it's a genuine Irmscher item, doesn't automatically mean its worth excessive silly money, I've bought a couple of Irmscher parts at very reasonable prices off a seller on here .