RIM is going through a transitional period with Blackberrys right now. In an effort to keep up with a smartphone market that looked to be leaving them behind, they will be releasing a new line of phones, with a more capable OPS system, later this year. They also have plans to roll out the much different QNX OPs system next year (on their handsets), which many analysts believe will allow them to compete more favorably with the iPhone and Android platform phones. It should be more appealing to developers and will offer platform flexibility, being able to run, among other things, Android Ginberbread apps.
So, it's not surprising that you're seeing price deflation for existing Blackberry models (and that deflation is evinced by a decline in RIM's ASP number). For one thing, the anticipation for the new products is no doubt suppressing demand for the old ones (though the RIM spokesman tried to deflect when asked about that during the last conference call). For another, carriers are trying to reduce their inventories of existing Blackberry models (and thus likely trying to force sell through with appealing pricing).
I don't know whether RIM's attempt to transform its product line (and remain viable in the smartphone market going forward) will be successful. But, it probably doesn't have to completely keep up with the flexibility, functionality, and ease of media experience that is making the iOS and Android platforms so successful. If it can just get itself close in those areas, its familiarity, and perception as secure, among enterprise users might be enough to make up the difference and allow Blackberrys to maintain a significant share of the overall smartphone market for a while.