Last week BlackBerry announced that it had 72 million subscriber accounts. The current market capitalisation is $US5.4 billion and enterprise value (i.e. excluding net cash) is about $US2.8 billion.
That implies a net present value of about $US40 for each account. This is quite a drop from early 2010 when the value was $US866.
The graph of BlackBerry subscriber accounts and EV/account is shown below: