Due to the recent company in assessing whether import assets inventory system (with PDA scan qr code, upload the backend system), but I don't know how to calculate the cost benefit, so ask to see if anyone can guide, there are several assumptions as follows:

1. A total of 314 units at home and abroad, PDA purchasing cost per NTD 25000, a total of 7850000 NTD,
2. The APP development costs about NTD 3000000,
3.1 employees monthly salary assumptions NTD 45000,
4.1 units assumptions have 10 computer need to inventory (+ screen, which is 20 devices), artificial inventory takes about 1 hour (looking for equipment, paper, system input... And so on), if the PDA inventory about 20 minutes,
Do 1 time only 5.1 years, PDA is expected to use 5 years in new time,

I wonder if that isn't there any way to assess the cost effectiveness, worth to import?
I come from Taiwan, so the NTD currency, thank you.