Tom Tom Go 540 Live SatNav was approx £300 delivered when ordered it from dabs yesterday.
When I checked back today, the price had dropped to £268 - everywhere else seems to have a price of £299 (usually delivered).
NB: This is effectively a pre-order, as dabs say in stock 1-2 days and other places (e.g. Dixons, Amazon have a release date of 24/10 - 31/10). Also note, that in the past I have bought from dabs, and found that in stock 1-2 days is not necessarily accurate, so you might not necessarily get it any earlier from them.