For a player of his potential I'd say it is.
Nice bit of hyperbole as well by mentioning Messi.
I was completely serious. Cabaye had a 4 million release clause, now that is what I would call really low for a player of his ability. 15 million for a youngster with a lot of potential really low? Nah..
Consider the fees for Hazard, Oscar, and what Gotze and Muniain would cost. 15m is pretty good in comparison.