I've spent ages looking into this, and bought quite a few to trial. I've found what I think is definitely the best of the bunch - its waterproof, does proper 1080p at 30fps and 720p at 60. Video quality is really superb, its waterproof, durable and handles repeated recoil (at least a days trial on the sbs shotgun on woodies didn't do any harm!). There are a LOT of cameras out there that claim to fit the bill and in my experience don't. They come with a variety of mounts including a rifle/scope mount.
None of the others I've looked for manage all this - even far more expensive offerings. Don't confuse this with the nasty plastic or low-res cheapies with naff CMOS cameras and exaggerated fps claims - these are proper jobs!
I am looking at the feasibility of a group buy. The price will work out no more and probably less than you would pay direct or on evilbay from China. I will (genuinely) not be making a huge amount on it, but aim to cover my costs - I'm not a retailer! If I do end up going down this route I'll get a month's trade subscription on here so I don't upset anyone.
If you would (genuinely) be interested please post on here and I'll cost it up. I suspect (depending on numbers) the camera will come in at around £60.
I will in due course post up some test footage and images of the camera/mounts etc.