But fandom doesn't want them to save money, look at the whining that went on because they used an Ood in the Doctor's Wife rather than the new alien Gaiman had designed, or because of the gang of aliens who turned up at the end of The Pandorica Opens because they just used every old costume they had to pad it out?
Clearly money was wasted, I never liked the console room retread and I like the one we saw in The Snowman a lot more, and there were the fatleks (of course you could argue their redesign was less about Moffat and co wanting to change things than the merchandising people demanding it) but they do seem to have embraced money saving where they can (filming mutilple epiosdes when they went to Spain/Croatia).
I don't think there's one single reason why the number of episodes have dropped off, I think its a combination of things, from Moffat perhaps not being well organised enough to the Beeb cutting costs--but then most of us really don't know one way or another. I have no idea how much creative control Moffat has compared to RTD, or, more importantly, how much money he has to spend. It wouldn't surprise me if RTD had more control and a bigger budget, certainly he seems to have been given the green light for most things he wanted to do (up to a point) Dr Who confidential? Sure! Torchwood? Why not! Sarah Jane Adventures? Of course. Let's face it if RTD had really pushed the issue we might well have got (shudder) Rose Tyler Defender of the Earff!