There's a plethora to choose from. I bought an Apeman C550, am very happy with it. Only downside is that it's front only.
Something to keep in mind (not so much for FrancisK, more for the guys looking), make sure that there's an option to save the settings. I ordered an off brand ("comparable to the Apeman you've previously ordered") with a rear camera, but it wouldn't save the settings. So every time the vehicle powered off (even with the hard wire voltage sensor kit), it would go back to Factory Settings.
Now they have dash cams that, with the applicable app, can download the video directly to your phone. I've got my oldest shopping for one of those (that'll be one of their Christmas presents, right now they have an inexpensive Wallyworld one that plugs into the cigar socket). If the price is right, I may get two and replace mine as well.
I've seen them as high as $500, as cheap as $25. Even with the $25 one that powers off with the cigar socket, something is better than nothing.