Ah, time for more sad revelations about how the business of pro tennis marketing works. Sorry to spoil Christmas for you kids, but there is no Santa Claus. It is fairly common practice for racquet companies to send a bunch of racquets to top players (sometimes at tournaments) for signatures, that are then sent out for auctions, charity, raffles, promotions, giveaways, etc. In fact, I have such an autographed racquet from Sampras's playing days. These racquets are generally the stock/production models that they "appear to be using"...i.e. the production version of their paintjob.
Nadal does, as many have noted, use the original APD (non-cortex) in competition, but Babolat sends out APD WITH cortex for promotional uses like this. So the racquet in question may well have an authentic signature, and he may even have hit a few balls with it to legitimize the authenticity, but it certainly is not one of his actual competition frames from Wimbledon, and it clearly has real cortex on it. The stringjob is also apparently unused.
The racquet may be worth something due to the signature, etc., but anyone who thinks he's getting the actual frame Rafa won Wimbledon with is kidding himself, as long as the racquet in question is the one in the picture. Only the market can determine what it's worth, but it would appear to be worth a lot less than is being asked. Still, if the bidding is part of a legitimate charity auction, as they state, then the selling price has nothing to do with market value, and the more it goes for, the better the charity does. So as long as the auction is on the up and up in terms of it beneficiaries, I suppose a good end will come of all this. Definitely some moral mushy ground, though...(i.e. is it good to be deceptive for a good cause?)
N.B. If you look at the wording, it says it's a "Framed and Signed Rafael Nadal Racquet From Wimbledon 2008.". It doesn't actually say it's a racquet he played or won the tournament with, so they may be legally covered, although it's definitely misleading.