Good Approved Cheap Dash Cam

[Raf Welsh Passat]

Looking for good dual dash cam, preferably with separate back camera to be wired at the back of car.
Nothing too expensive, rather spend dosh on a car and all bits to be done with it.
Of course something that is approved by insurance companies, so question: can most of dash cams be approved as long as it does what it says 'on the tin'?

Found something looking rather good on eBay
Elephas Novatek front 1080p and back 720p, night vision cams

http://www.ebay.co.uk/itm/ELEPHAS-Novat ... 2067639402

Any advice appreciated