Free: Contests & Raffles.
I can't say good enough about the basic or even fancy Bushnell Trophy cam. If you look around sometimes you can find some very good deals....I picked up my last one at Cabellas for $125. Biggest draw for me even if you do spend a little more than 100 is the size is very compact, easy to use, and they simply go a long long time on 8 AA batteries. I know you can spend less but if you are changing out much more expensize C's then really you aren't saving much. Amazon, Cabelas, Bass Pro...just poke around and look for good deals.
Moultrie M80XD, $99.