I recall a story 4 months back or so, that the Clinton campaign and SuperPAC had "blocked out" huge chunks of cheaper ad slots early in the campaign in swing states to force the cost up for the Republicans.
Is that factually correct and if so, is that having an impact on potential Trump campaign ad buy decisions?
It has some but they aren't cut out, but it probably hurts outside groups more than the Trump campaign. Actual campaigns are entitled to the discount rate. And there are a lot of advertising slots available in general for most big media markets it is hard to box someone out. Remember back last year, just two fantasy football websites spent over $200M in advertising in the fall.