In the US you can buy national ad spots on major channels pretty cheaply (couple hundred $ per spot) if you buy "remnant" inventory. Basically that means that t

In the US you can buy national ad spots on major channels pretty cheaply (couple hundred $ per spot) if you buy "remnant" inventory. Basically that means that the network hasn't sold all of their "run my ad in the 9:22am commercial break" spots and so you can try to by a spot in the "morning" day part and it might run in the 9:22am commercial spot...or it might not. But they will tell you if/when the ad ran at some point so you can go back and check your stats. Attribution is kind of a bitch, but the methodology above tends to work very well given the right traffic size/mix.