I'm currently using Prime for Students which is $39/yr, but I've taken advantage of so many deals that I'll probably keep my prime going even after I'm out of school.
Whenever I buy a new game using the Prime discount, I'm usually able to sell it on Kijiji around for a few bucks under what I bought it at. For example, I got Horizon for $70 (got $5 off for that RE7 error) and sold it for $60 a week later. That and the free Twitch subs make Prime worth it for me. 2-day shipping has always been pretty good for me, too.
You finished Horizon in a week ?