Here is a commercial one that we have used for CQB and Riverine Opns.
http://www.helmetcamera.com/
I work with surveillance and video recording equipment for tactical opns and there are a lot of different ones on the market. The price range is from 100-thousands of $. also I build custom ones as opns requirements develop. Start with the link and you can go from there. Budget is a big issue.
Another option is get a fixed Litstick camera, build a battery pack and use your small DV handy cam or DV recorder. You can make your cables to fix your requirements.
Good luck.