Yeah, they pretty much only drop in price right before a new model comes out. And then a lot of times it's just refurbs on sell--but they are good as new and have the same warranty.
The PW came out last fall, so I wouldn't expect a new one before then. And they haven't always done yearly updates so it could be 2014 before a new one is out.
If you're a heavy reader, I'd just pick one up rather than waiting since you're probably looking at 4 or 5 months at the least before any sale, and with them being cheaper than older models any sale will probably just be $10-20 off tops anyway for the cheapest model (wifi with ads).