These are all very good suggestions but the fact of the matter is if you spend less than $100 on a trailcam, you are taking a very big chance. Not that any trailcam in any price range might not fail, it's just that the chances of failure in a cheap cam is much higher. You might get lucky with a cheap cam or you might not. I say spend at least $150 or so to increase your odds of getting something decent.
Blessings.......Pastorjim