It all was fine till item 4. Without that, the cameras should become very expensive.
But there are ways to convert a wired to a wireless connection. And I think what stops folk is that most never want to become a master of IP addressing and networking.
Sorry, nothing I've seen hits all your points for the prices you mentioned.
-> If you ever get back to the PC host, consider what I used for mine. I used a (simple?) Emachines e250-1152. When the screen turns off the power draw hits about 5 Watts.