The Wagner Paint Crew 770, that is. Not in a million years would it have occurred to me to buy a paint sprayer, but Sarah - with a not-atypical focus on "how can we get this done faster" - suggested it and I have to say boy was that a good idea. I put 5 gallons of primer on the walls in a little over an hour, including the entire ceiling. Try that with a roller. I was a little scared of it at first, but got the hang of it pretty quick. $200 at Lowe's. And even if we never use it again after this project it will have more than paid for itself.
There are some tricks to using it (I recommend starting off in a place no one will ever see) and it apparently needs to be cleaned pretty well to ensure that it'll keep working, but I can't recommend it more highly for what I gather is a pretty entry-level paint sprayer.