I bought mine from Moneysupermarket.com. The cost was around £45 for a year's policy including 17 days winter sports.

It's by no means the best cover on the market (only £2k for baggage), but it's perfectly reasonable if you just need a bit of peace of mind.

One thing that varies between insurance companies (apart from the cover levels) is that the cheaper ones might take 3 months of arguing for a payout instead of one.