The continuing economic crisis is causing ad rates to plummet even during the typical highest demand time of year, 4th quarter. The largest advertising categories Automotive, Retail and Financial have experienced massive cut to advertising budgets in response to the economy leaving huge amount of available inventory in local and national television.
In theory, due to low demand on television (lower rates) the cost per lead should remain constant. However because of inertia, the television rates are not dropping at the same rate that response is dropping. This is a temporary state, and if the economy continues as is, cost per leads will be corrected with lower station rates.
Even as advertising response declines, it should be noted that demand is quietly accumulating at its normal pace. Your target market may not be responding at normal levels, but the demand is still there and is accumulating as time passes. The response and sales will be realized when your target finally responds out of necessity.