The dates to put in your diary are: Sept 15th, Europe, September 19th North America and October 21st, Japan. There's going to be a few different Move bundles and deals available at launch. We should hear more about those shortly.
If you own a PS3 already, Move will cost $49.99 and the navigation controller (adds directional buttons, an analog stick, and two shoulder buttons into the PlayStation Move's control scheme) will cost $29.99. No word on the UK equivalent.
Cheaper than we thought, though. Just need some decent games now.
Edit - The UK Price, which will include PlayStation Move and the PlayStation Eye will be £50.