where can I get a fully functional and working ps3 at a price of $100 or less?

ask some friends they might have one they can sell you for a 100 or less or look at ads in the paper

The best place to look is eBay. http://www.ebay.com/bhp/used-ps3-console

I'm not sure that you will find one for $100 or less though. At that price you have to consider that something might be wrong with the console. You are taking a big risk buying a PS3 at or near that price.

Ebay,

Amazon,

Gumtree,

Or go to a local stock exchange/pawn shop. My local sells 120GB ones for about £40($66) so just look around!

I would go to amazon and look into the used files, alot of people sell great things for used, also go to ksl.com and look into the classifieds. Im sure someone is going to sell it for cheap there!

ebay or amazon. There is half.com which is like ebay.