Bidding goes up and down for all/any keywords advertisers are looking at. If the leads arent getting them in the plus for any particular keyword they're paying a dollar or more for, then without a doubt they will drop that puppy down to a penny or so. I've done the same thing. For one keyword in particular I was paying x.xx per click and it kept climbing cuz some other guy was trying to outdo me for top spot, after a while I gave up and let him have it, then set my click bid to 5 cents knowing my return was better. He then dropped his slowly to a more suitable amount, when i tried to creep up again he just kept on me. a virtual rollercoaster ride. Either way, the cost per click (pay per click) can be a dollar or two one week, and 5 cents another.