I don't know about the US situation, but the European prices tend not to drop very fast before a new model is introduced.
Not too much even after the introduction of a successor model.
If we look at the prices of the K-7 and the K-5 over time in the Netherlands.
The K-7:
Have a look at the K-7 price development after the start of the price development of the K-5.
The K-5:
The K-5 was introduced October and became generally available around december 2010.
You see that the K-7 price dropped until Januari, but that more or less stopped then.
It even became more expensive after that.
If we have a look at the K20D price development:
We see that the K20D price did more or less the same after the K-7 was introduced (August 2009).
If history is an indication for the future, I expect the K-5 price to be at its lowest point around 3 months after its successor is introduced.
What means that you better wait.
- Bert
NB Price references are taken from: tweakers.net and based on Internet prices.