Would be great to buy as cheap as possible camera to just run and have RTSP stream. Are there any suggestions?
As you didn't provide what you need the camera for, I can just recommend some general cameras.
- Ansice Camera this is ideal if you want to hide the camera. ($12.60)
- Raspberry Pi with camera You have to have some knowledge with Debian based Linux distributions to set this up, or follow a tutorial (very easy). (~$65)
- Boomlens Camera standard CCTV camera. ($16.85)
- Cambase Camera Ideal for outdoor surveillance with wall mount, supports HD. ($26)
- SV3C Camera Outdoor and indoor camera, FullHD, Waterproof, PoE(Power over Ethernet), infrared (Night vision). ($46)