Give Adam @ Renault Wolverhampton a call for a quote on the rear Sachs. He might be able to do a better deal for you than Wests.
You can contact him on 0844 558 8799.
Sounds like a good example, especially considering all of the important maintenance bits have recently been done (belts & dampers).
I'd put it up for £6k personally and I'd take the carbon bits off to sell separately.
Another vote for the Sportlines here. I'll be getting some in the near future.
With regards to fitting 182 Cup rear dampers, I personally wouldn't. I can't imagine they'd be very well matched to the front Sachs dampers.
As has been mentioned, Wests Renault (who advertise on ClioSport.net)...
As above.
It's also worth noting how easy it is to spend a few grand on these cars if they haven't been properly maintained by the previous owner.
Add another grand or so to your budget and you should pick up a good one.