The state of Texas here in the US is deregulated and actually has a website that lets people know which company is offering the cheapest power:
http://www.powertochoose.org/
The trick is to sign up for a fixed rate vs. monthly, because then you'd be at the mercy of the commodity markets.
Well, the fixed rate is going to be higher because it assumes higher energy rates. The premium you pay for a fixed rate is basically an insurance cost, which probably includes added profit for the utilities. Chances are you'll end up paying less on a variable plan.