Age of the devices

I have to generate a report listing the devices (Laptops and desktops) and their age (how long has it been since we bought the devices. I would need to generate this data monthly to plan for the laptop / desktop refresh.
 Currently, I looks like the only option is to combine the device data with the Purchase information - I don't think I can directly get this in a report - so need to generate the data in an EXCEL file and then combine this report.

Can you create a new feature in the report to pull the Purchase date of the device from the Purchase Order data, add a custom field to calculate the age (years and months - which would be the difference between the current date (today) and the Purchase date) so that I can generate one report for the devices with this feature as well ?

Regards
Bala