To trace the buying part, you can use analytic accounting. Install the account module and enable the analytic accounting usage under Settings --> Configuration --> Financial. 

Then make sure to create an analytic account for each of your employees in the database. 

Afther that is done, on the invoice (and the purchase order as well) you can link the analytic account of the employee to the invoice line. This will add a link (and the value of the product) to the defined employee. Check the analytic account information to see what lines were defined for it, so you will have an overview of all gadgets bought for that employee.

This is a bit of a workaround but it might help.