Does it have the display case and accessories? If so, it's a really good deal.
Truth is, if it's in as good a shape as he says, it's still pretty good. I sold an identical gun new in the box and unfired, but with a damaged case for $600 several months ago. The 6 1/2-inch is rather uncommon in nickel.
Holy cow! A 29-2 in good condition for $450? I haven't seen a deal like that for some while. I like the 6 1.2" barrel for the 29, too; for my money, it's the best "fit" of barrel length to that gun/caliber.
Buy it! I own one in Nickel with the 8 3/8" barrel with walnut case. Sadly though the velvet lining is all but gone and only the plastic molding still exists with top drawer cover. The cleaning rod, brush, swab are still intact. Time and storage conditions I assume. $335 to the original owner 4 years ago. Condition is excellent.
The going price for used handguns seems to vary a lot with locale. About 4 years ago I picked up a mint 4-screw 44 made in 1957 for $280 at my favorite gunshop. Late last year I picked up a slightly used 4-screw nickel in the wood case that was made in 1958 for $500 at the same place. But it had been lightly engraved (not by S&W) so I am not sure that serves as any reference at all. Most of the 29-2s I run across seem to run about $400 without the box and $450 with so I would think you are in the right ball park.
Like land, they ain't making any more so one might keep that in mind. I don't see any way they can go down!