^Yeah, there was some kind of computer problem with the pricing. I think some of the earliest purchasers might have gotten the lower rate, but it'll probably be fixed now.
I got my copy of the standard Region 1 set today. I don't have copies of the previous series to compare (yet), but from the description above it sounds like it's the same approach as series three, complete with difficulty sliding the bulky interior package out of a tight slipcase.
So far I've watched the deleted scenes for "Voyage of the Damned" (nothing too interesting), Howard Attfield's scenes from "Partners in Crime" (goodness, the poor man was visibly ill), and the first David Tennant video diary (a joy to watch- Julie Gardner's enthusiasm is infectious). I've also listened to the "Partners in Crime" audio commentary, which as always with RTD commentaries is a mix of production tidbits and irrelevant comedy. I love it.