I'm pretty sure the xbox already got a price cut, elites are 299 and pro's are 249. But they're trying to sell out all the pro's so there wont be any when they sell them all, just elites.
As for your harddrive question, it really depends on how much games you plan on playing. I would just get a 60gb if your only planning on playing a couple games. If your going to download a ton of demos, and play a ton of games I would spend the extra 50 and get 120gb.