Well considering last i heard WD were still pulling Crocs and Pythons out of their slider factory(this information is several weeks old). i don't know when prices will start going back down but i'd say a good 9 months from now.
I've been keeping an eye on 2TB drive prices and they topped out at about £170 then went down to £130 ish and at one point not that long ago they were at £100 so I thought we'd weathered the storm but seems now they've gone back up to £120-130. I might shell out for one when they are back down to £100
Like I said before, keep an eye on the hardware bargains thread, plenty of 2TB drives on there for under £100.
I saw in an email from scan I got the other day, they had a 2TB external drive, for £71.99. Think it was a Today Only thing, but now its still only £97.44, which seems quite good for 2TB.