I have never used one so I can' t comment on different models or what ever. There are directions online for building your own and guys have pretty good results with those for around 100 bucks apiece from what I remember.
http://ca.geocities.com/petergward/home.htm
I know a lot of people use them I' m not saying they are wrong for it. I just wonder where you draw the line. You could set up several cameras and set up a monitor and hunt from your lazy boy if you wanted.
Again, I' m not saying they shouldn' t be used but we do need to define some rules for using them, IMO.
-Chief