Cheapest standalone home surveillance option? (Haven alternatives?)

See also: Self-Hosted CCTV (IP Home Security Camera) System Questions > Does Privacy Guides have a recommendation for a secure & private system for security cameras for a home or office? I originally asked this question on the Security Stack Exchange https://security.stackexchange.com/questions/286737/dropbox-resistant-wired-ip-camera-system/286738 My biggest concern above was: if you’re running an ethernet cable to a wired IP camera outside your house, what’s to prevent an attacker from plugging in their own battery-powered raspberry pi or packet squirrel (drop…