It's important to note that buying out machines and auto hacking them do
count towards this. Most of the hacks I accumulated were done so this way.
In addition, I would advise to manually hack machines only in the early stages of the game, as they sometimes become rather time consuming later on.
Playing on Easy difficulty will get you this achievement faster, due to more money you find and auto hacking devices.
The best things to buy out are vending machines and health stations as they are usually cheap. Try to avoid expensive buyouts like safes.
If you are going to purely do manual hacking, I'd recommend the following Engineering tonics:
Speedy Hacker - Reduces flow speed. Location - Found in Painless Dental in the Medical Pavilion. Also available for purchase at Gatherer's Gardens from Arcadia onwards.
Focused Hacker - Reduces amount of overload tiles during hack. Location - In the entrance to Fontaine Fisheries in Neptune's Bounty, frozen in ice near the pneumo tube. Also available for purchase at Gatherer's Gardens from Arcadia onwards.
Hacking Expert - Reduces amount of "bad" tiles during hack. Location - On the desk inside the entrance to the Research Laboratories in Arcadia