This is the one form of advertising that can include actual bidding when push comes to shove. When someone wants the time slot you've already purchased, they'll offer more--and bump you out. You always have the opportunity to up the price you're willing to pay, of course, but many businesses can't afford to get into that kind of bidding war. When is that most likely to happen? The fourth quarter of the year is when lots of inventory is snatched up by holiday ads. And anytime a hot political race--either local or national--is going on, you can be sure the competition for time slots will increase. Unfortunately, these are also the times when small and midsized businesses really need coverage but get shut out.