As I mentioned on Twitter I know a lot goes into these decisions and, I agree, I think cost was a big factor if not the deciding factor. It also makes me think about the DVDs and how different music was used/scenes were cut because, we assume, music rights were not secured for the DVD release. Which is a cost cutting measure. So, perhaps they were looking at the expense of the show and not quite getting the ratings they wanted?
Sky1 also has purchased a lot of foreign/US television productions and seem to only recently trying to go more in-house (or in-country). Which means more expense and potentially more risk. I mean, if a show is a hit in the US it's likely to do well for them too. But I think it's shortsighted for them to bail on a show, with some buzz, with potential to grow, after only one series. If after another eight episodes (perhaps scaled down episodes) they decided not to move forward, I'd get it. But imagine if ABC had decided to cancel 'Scandal', which was on the bubble, after it's short first season?