Yeah it looks like the dancing games sort of fell off once the trend of "Guitar Hero" and "Rock Band" games picked up, because I can't find anything about a DDR for PS3. It's possible you might get it to work if you buy one of the older, backwards-compatible PS3s, but I'm not sure. I don't know how the pad connects to the system, and since the older controllers won't connect to the PS3, that'll probably be what stops you.
On the other hand, what the others are saying about the Blu-Ray player is true - it's one of the best out there, and if you're going to be gaming as well as watching BD movies, it's well worth the sticker price. If you're NOT going to use it as a gaming machine, there are cheaper Blu-Ray players that would probably be a better way to go.