One of the simplest ways to determine initial deployment cost is to simply add up the per-user costs associated with initially acquiring the hardware and software, add in the per-user costs for wireless services, and then add in the per-user costs associated with training and continuing education. The training and education costs can be determined by taking the total costs allocated for these elements, and then dividing by the projected number of mobile users. The combined per-user expenses arrived at through this formula will give you some idea of the per-user deployment costs of a mobile device.
For example, if you are paying $500 per mobile unit, $59/month/user for wireless services, and have a total estimated monthly training budget of $5,000 for 50 users, then your total first-year per-user deployment cost would be about $2,408.
You will then have to determine and add in the estimated expenses for service and support of these mobile devices (total budget divided by the number of mobile units deployed). These costs can be fairly high, though, with some estimates reaching $3,000 - $4,000 per user per year.
If you want to get really detailed, you can also measure the productivity of these devices by multiplying the number of hours saved per user of these devices by the per-hour cost associated with each individual user. This can get a little complicated, however, since you are dealing with multiple salary levels and people who do not all use mobile devices and application in the same way.