Is There Such A Thing As "per Inquiry" (pay Per Lead/sale) Tv Advertising?

I've heard of this concept but not sure if any are legit and most charge large deposits against future leads/sales. I have something I can promote on late night TV and not the best channels/times (at least to test) and this would be ideal if there are actually reputable companies out there without the upfront fees. Anyone have knowledge of this or know of any reliable companies to go with? It's one of those things that sounds too good to be true but believe it or not there are companies claiming to offer this to fill unsold inventory. It would be nice if there was a good company doing this -- that's why I'm posting. Hope someone can offer suggestions. Thanks!