Thanks guys.
The prices for the bigger Fuchs just seems to be crazy! I saw a set (7" & 9") a while back for £500 but decided not to go for them because I thought it seemed excessive for 2nd hand wheels.
I found a UK Porsche parts supplier selling split rim HRE Fuch replicas but they are £700
per wheel. 
Here's their site.
My search continues for a bargain!