Looks legit to me. The Box Set version has to be distinguished because the $169 Box Set version is the only retail disc that's a full install. The $29 and $9.95 discs are upgrades.
The disc's may be legit. However the procurement of them? Well that's another matter entirely.
Let's face it.... how on earth do you stumble upon a mac box set of 10.6 before it's released anywhere legitimately?
If they are the real discs, I'll stick with either A) they work themselves at Apple in Hollyhill Ind Est, Cork or that B) they are selling them after procuring them from a dodgy source, who possibly works at the forementioned.
Too much co-incidence that the seller is residing in Cork otherwise.