BBHub reports the it would be $845 per user, which factors in $300 for new equipment, some amount of money for accessories, 4 server hours per user for switch over, and productivity losses. Read the post on BBHub for more details, but it’s interesting to see that at least someone has tried to quantify the potential service stoppage. Based on your company’s Blackberry deployment, how much would this cost you? I bet it’s an awful lot of money.
One thing this doesn’t calculate (at least I don’t think it does) is the sunk cost of the Blackberry server and the cost of either buying Good or activating ActiveSync on an Exchange server.