anyone wanting to build one really should go to
www.jesseshuntingpage.com
and spend some time there. You can find the owl cams for as low as $40 sometimes. Probably $100-$125 total in the camera.
I don't know of anyone having problems with scarying deer off with the flash, at least not permanently.
I have built one from jesse's. Its a good site, with forums on a lot of stuff.
--Jim