Reddit reviews Abowone 4Channel 1080N CCTV DVR Hybrid 5-in-1 H.264 Surveillance Video Record System NO Hard Disk (1080P NVR+1080N AHD TVI CVI +960H Analog)

It looks like they run anywhere from $40ish up. You'll most likely pay into the triple digits for a higher quality one though.

Something like this would be an example of a cheap one, but I have no idea if it's worth it. It's a chinese rebrand. It's a 4 channel setup, with a 12v input.

I'd most likely go with a name branded one, to be safe.
What's strange is that a lot of these are cheaper than most FPV grade DVRs, surprisingly. Do note though... They aren't quite as user friendly, but they're far more capable. The noise filtering is unparallelled, as well. Crisp, clean recordings.

Here is the mobile version of your link