The problem with a plan like that is (a) there probably isn't going to be another Star Wars celebration and (b) it just makes too much damn sense.
How's this for another plan: If you KNOW you're going to sell more AFTER the show, announce it so you chop the vendors off a the knees. You make them question just exactly HOW MANY were made and they think twice before hoarding them for after-event price gouging.
Just think if all of the Vaders that went into the hands of vendors instead were left over and were selling now on shop.starwars.com? Jerks like Brian's Toys wouldn't be even daring to ask $80 for one of these!
I feel that the dealers inflated the demand of the Jorg Sacul too - at this point, he's down around $40 and many times the auction closes w/o any bidder. In another two or three years, I bet that figure will be available for about what you could get it for at Celebration 2 - the reason is that many of them fell into the hands of vendors, not actually the people who truly wanted them. Sure there was everyone at the event who got them and then the die-hards who couldn't attend who fed into the eBay frenzy, but after that, all that's left are those who pass due to the price tag and those who just aren't interested in GL's head on an X-Wing pilot body.
The same is and WILL be true of the Vader.