Hi Andy,
Keep an eye out on the internet and places like ebay USA as most of these heads went to the US.
I picked a head up last year for quite reasonable money from ebay. Guess I was just lucky!
I see them go for up to 1000 pounds but I paid 502 pounds for mine and am very happy. The flow in un touched state was a lot bigger than my fully flowed GS head, and now it's been worked over and ports opened up etc it should be a vast improvement!
Good to see someone else has seen the light
Regards and good luck.
Julian,
Will keep my eyes open for you.