It might be a fair deal and if it is I am thinking you will enjoy the bike. Closely inspect chain rings to confirm they are not worn our. Measure the chain with a rule to check for excessive wear. If the chain is excessively worn you might need to replace the whole drive train. Same with Wheels and especially the brake tracks. Any defects should result in price concessions. ANY!
For it to be a fair deal IMHO it needs to be in pristine condition. 12 year old carbon @ 30% cost of original seems steep.
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Sir Mark, Knight of Sufferlandria