I purchased my K20 at the end of its model run for $650 and it came with a 2 year extended warranty (unexpected but very welcomed).
As panoguy wrote the K7 was on the order of $750 to $800 and change, if memory serves me correctly.
In January, I upgraded to the K5 for $750 new from Samy's Camera over in LA. At the time it was believed to be a pricing error for a day. I have no additional knowledge if it was an intentional sale or an error, but they honored the order and delivered the camera. I think that there were about 15 to 20 of us who scored a camera at that price (and the next day the price went up to $1100). I think for new that will be a low point. Considering Pentax's new pricing policy and I am going to guess from here on out, $800 to $850 - but I have no special knowledge. When I was saving up for the K5 or what ever, that was the price range I was thinking would be attainable.
One other aspect to all of this I would like to throw in for consideration - the 2 year extended warranty. They were out of stock for quite a while up to several weeks ago. The out of stock lasted for quite some time, I would say at least a couple of months. Now the extended warranty is just a fancy printed postcard with a serial number on it - no real manufacturing needed - and yet it went out of stock. I will say, that I have become quite accustomed to having that 2 year extended warranty - for a total of 3 years of coverage. However, to get it, you need to purchase new and have (keep) your sales receipt (showing who you purchased from and the date). To me this would be a consideration - especially for the $20 price. Also, as a side note - you can purchase from one retailer and then purchase the warranty from another. B&H along with Adroama are the two that usually have the extended warranty available.
Anyway, that's my guess....