I don't think it will be that long to see price drops (Amazon Wireless currently has the Charge at $199.99 for a NEW subscription, $250 renewal). Costco, Wirefly and LetsTalk also have the phone for $250. Personally I think that both the Charge and the Thunderbolt should cost around $100 since without $720 or more for data services over the life of the contract they are pretty much fancy feature phones!
The real wild card ATM is whether or not you can afford to wait past June when unlimited 4G dataplans may go the way of the dinosaur; If you are a "typical" data user under 2GB a month, it won't matter much but who on these forums is a "typical" data user? Heck, stream a couple of movies and you'll be over your quota in a hurry.
Got to be careful not to be penny-wise and pound-foolish...at least that's the argument I'm using with my wife to convince her for us to switch to 4G phones...but you can see how far that's gotten me with the current prices (and I DID find two Thunderbolts for $100 apiece through a Vz reseller)!!!
Good hunting, however!