Hawk, having dunked and scrapped both a video (in 'weatherproof' case)and a still camera (in a Ziploc bag: bad idea) while steelhead fishing in Alaska some years ago I'm going suggest that you either go the whole hog and get a video cam housing that's waterproof or bag the video idea entirely and go with a waterproof camera. The 'rain/ splash proof' covers are priced right but won't be enough when you(invariably) drop the camera somewhere really wet (e.g., the river).
As for the housing, dive shops sell them or make them, but they are indeed expensive. You should contact the two Fisherman's Heaven principals Kevin and Mike as they use Sony digital cams with waterproof housings to get super underwater shots for their TV shows (contact c/o
www.fishermansheaven.com -- there's an email address on their home page).
For a still camera I bought a Minolta Weathermatic 35DL waterproof camera last year. Good to around 30 feet I think, and goes around the waist in a zipper closed pouch so it's handy if you're wading and want a shot of the world record before you release it. The price was right, too, at $150 but there are two drawbacks: (a) when you take the camera out of the pouch, if it's cold out you may need to wipe condensation off the lens and viewer (or else get some fuzzy pictures) and (b)it's not digital. Photo quality otherwise is excellent, and the camera's tough as well. For the money beats buying 10 of those disposable waterproof cameras any day and it's the sort of thing you take on a family vacation to the beach and never worry about it.