Just accessed WOOT and found they are selling some cheap night vision goggles that might be good for checking on bats without disturbing them. "Spy Net Recording Night Vision Goggles, 128MB Built-in, 1GB USB Drive, 640x480 (VGA) 30fps(s)". The price is only $35 including shipping. Yes, that is too good to be true for anything really worthwhile, but, the guys on WOOT are giving them surprisingly good reviews, and if you monitor WOOT very often the members are real nitpickers. WOOT is at
http://www.woot.com. You have about 6 hours to place an order. For $35 what can go wrong?