Help! Can I use 4 nanny security cams (those listed on ebay for $30 or so) simultaneously without inteferring each other??

["owner" <wildlilysale@xxxxxxxxx>]

I am very interested to buy 4 or more of these cams as below
http://cgi.ebay.com/NEW-WIRELESS-NIGHT-VISION-SPY-CAM-SECURITY-COLOR-CAMERA_W0QQitemZ5852055181QQcategoryZ48632QQrdZ1QQcmdZViewItem

or

http://cgi.ebay.com/NEW-WIRELESS-NIGHT-VISION-SPY-CAM-SECURITY-COLOR-CAMERA_W0QQitemZ5851722357QQcategoryZ48632QQrdZ1QQcmdZViewItem

Can anyone tell me if I can use 4 these kind cams for a property
simultaneously, ie. each show own view without interferring the other
cams?  In other word, can I tune each cam/receive with its own
frequency different from other cam/receivers?

None of the ebay seller replied my email. Please help!