You mentioned quality, location and price for each product/service, but not the times and ages? The engineer must be willing to leave a cellphone beside their bed every night, to be woken up at any hour to fix a problem which may or may not be related to the computer systems they work on during office hours. They must be over 25 yrs old, i.e. "mature enough", but under 34, i.e. with plenty of energy to work 12-hr days, "still not cynical", etc. Their track record must be in 2-yr blocks of uninterrupted service.