With a ViP 612 DVR and three 211k single-tuner recievers, you're still at only four tuners (the 612 only counts as one). They'd probably upgrade the dish and a 612 for free. You can buy the 211k from
DishStore.net for $169, just so you know, but that'd be a $507 investment on your part.
Ask them first to upgrade all of your equipment for free, and if they don't say, "Sure, right away," then tell them that DirecTV has offered to do your four-room install for free. That should change their tune. Don't let them try go get away with installing two 722s, either. Insist on HD in every room, because that's what DirecTV would do.