Here's a link to a company that makes and exports cheap HD cameras that are light, small and waterproof. The new GoPro Hero 3 Black is due for release in the UK soon and will be around £350. All these cameras are around the £100 mark and are fairly good quality by all accounts:
Digital Waterproof Camera - Waterproof Camcorder
And here's a link to a review of one of these models:
