I've seen them come up in the PH classifieds and on ebay - or you could try douglas valley and bell hill breakers - but they tend to be pretty pricey wherever you get them.
Be careful - the Chimera ones are slightly longer, so you'll need to lower the mounting points. You're probably aware of this already, but whoever fitted the current struts to my S3 wasn't.
Got a pair last year on ebay paid £49 could not beleive no one out bid me, this was the second time I tried to buy a pair, first time I went to £90 and still got out bid.
Now I have a pair, I am very pleased, they look GREAT.