So before I go ahead and purchase PlayStation Plus, I wanted to know if I could share it with 2-3 other users on a single PS3/4 system. I just would like to know if I could buy just one subcription of Plus for 3 users (NOTE: These are "Master Accounts" and not Sub-accounts) or if I have to purchase 3 different subcritions... I would hate to spend at least $150 if this was the case.
What do you mean "Share" it?
Only one account will be able to access all the feature of Plus. That's the account that purchase it. Any free game downloaded by the Plus account will be able to be played by any other account on the system. Only the Plus account will get the free games and discounts, cloud service, avatars, themes, auto-update. If you're talking about the PS4 the other accounts will be able to play online as long as one account on the system has Plus.