Adam actually mentioned in the online Aftershow that one big reason they waited so long to do SW was being able to afford the clips.
And then he laughed. He was joking, I doubt the cost of those clips for the movies would have cost "that" much, really. Especially given they were pretty short, minor, clips for 30-year-old movies that pretty much everyone has seen.
I think it was the kind of joke that was based in the truth. No, it didn't literally take them ten years to save up enough money to afford the clips, but that was a facetious way of saying that, yes, the clips were expensive. Thirty years old or not, they're Star Wars
movies -- and they're Disney property now. So of course the clips are expensive to license.
I was interested by Adam's discussion of Han shooting first. I've always been bothered by the pride people take in the idea of Han shooting first, as if there were something admirable about killing in cold blood. But Adam's explanation completely turned that around: Han shooting first is important not because it's heroic, but precisely because it isn't, because it establishes his moral failings at the start of the saga so that his growth into a hero over the course of the story is more meaningful. So it finally makes sense to me.
(Well, that and the fact that the altered sequence is very awkwardly executed and requires Greedo to miss at point-blank range. I've always understood that part of the dislike.)