I know others have seen it and they say it's a very nice car. James, the seller, is a regular contributor on 968.net and he's talking about it in this thread. http://65.61.16.109/forum/topic.asp?TOPIC_ID=7138
A CS with Air Con is a bit unusual and a nice addition IMO, he says it has an LSD which if you want the most fun on the track then this will certainly help you smile more. As to the price, it's a LHD so it's price will be lower than any similar spec CS. So it needs something to justify the £12k asking price - well it's average mileage, so nothing extra for that, it's not an M030 version which would have helped the price, it appears to have had a of work done to it but that doesn't raise the price in itself.
It's a funny thing with 968's and especially so for the CS, if it's in the right condidtion and the car that does it for you then you might be hard pressed to find another one in such good condition and in the right colour/spec, in that case it's worth it to you. But for example, i was looking for a Sport, last summer, because i needed to carry my kids around occasionaly and i ended up buying my 94 LHD CS with 52k miles, it didn't have a full OPC service history, it had the factory fitted comfort pack, which puts in sports seats in place of the buckets, Air Con, electric boot release (thank heavens), central locking and 2 rear seats for the kids. and i paid £8k for it last September.
Oh. and BTW mine is in superb condition as it too had been lovingly looked after and only having low mileage on it.
good luck
Del.