If you go cheap, go big... Bunch of 4MP cameras that are cheap and suck. I love eating up storage with crappy night video.
Depends on what you need it for. Daylight with the sun lighting the object from behind the camera, no shadows, no need for motion detection from camera to recording device and so on, it could be fine. Really depends on your needs and the environment. I could buy a recommended Dahua or Hikvision and have total crap results and pretty much no camera would work in some environments.
If it is $30 bucks you want to spend, do it knowing that the camera is most likely going to be trashed. Worst case, you get to see how bad a camera can be. Tear it apart and see the guts.
Shit, I have a couple of boxes filled with crap cameras that are better than $100+ dollar box store cameras.
Good luck and feel free to post your results as most people are ok with expressing their opinions about cheap cameras.
If you want to buy a cheap camera, go to aliexpress and look for the IMX290 with true WDR for around $50. If you want to save even more, go with AHD and the new IMX327. None will compare to Dahua Starlight, but will be ok, just ok, for the money.
Forgive me, I have rambled on,
Chris