To watch for who is laying what egg you can get any type of wireless camera - but you would need for it to be able to record to a hard drive of some sort so that you can go back and review it.
We have a video security system that we installed ourselves. With the hard drive, power supply, cameras, programs, etc - it was well over 1,000. I need 4 more good cameras - but that's another 800 bucks and it will have to wait.
We have 4 cameras that are color with night vision and 4 cameras that are just black and white and don't work at night. All 4 of the night vision cameras are on the house - One on each door, one on the driveway that also covers another door. The last night vision one is on the house, but faces the chicken house (about 30 feet from my house). I can monitor for predators and such day and night. This camera also covers the gate to my horse field. The other 4 black and white cover various parts of the property.
When we get the barn finished, I will be putting cameras outside and inside of the barn to monitor all activity. They will be wireless so we don't have to run 300 feet of cable to the barn.