The price of the sale was not publicly released, for the most part all we know is that Qualcomm just bought what appears to be quite a large number of patents that cover early mobile OS technology, among other things. Although the numbers are unclear at this point, it appears as though 1,000 of the patents were from outside of the US.
HP acquired Palm 4 years ago to the tune of $1.2 billion, in what many describe as a patent grab. A move that sees companies scoop up as many key patents in technology categories they deem on the rise, in this case mobile computing. As some have suggested, it would appear that Qualcomm is doing the same thing.
While to some it may seem curious that Qualcomm would be interested in such a large number of old patents, companies like Qualcomm amass large quantities of patents in order to protect themselves against possible future infringement claims. The idea here is that with such a large number of patents under your belt, if someone ever tries to put infringement claims against you, you'll likely have a couple registrations of your own they're violating. Beyond that, Qualcomm will likely use the intellectual properties to pull out licensing fees from smaller mobile tech companies as well as for leverage in future deals.