I paid £500 for a DAS 4 day course a few months ago. One day cbt on the 125, two days on the 500, morning on the 500 and then the test. Dont forget about the theory test which is about £25 on top. Although it says a 4 day course, the 2 days on the 500 were only about 4 hours, with only about 2.5 hours actually on the bike. It does sound alot of money but its well worth it once you pass!
Dont forget to budget AT LEAST £500+ for all the gear, and youll need well over that if you want decent stuff. Having said that, i got all my stuff brand new from a show and it cost me about £300, in the shops it would have cost me £850 at least.

It was the BMF show by the way, the next ones in sept/oct i believe, so if you book your theory, training and test now, it may work out about right for when you pass.