TL;DR: Until October 27 at 11:59 p.m. PT, you can get a 1TB portable hard drive and 1TB lifetime cloud storage for $89.97. Files really do build up over time, and some of them are hard to delete.
Amazon still has some sweet storage deals after October Prime Day: Get the Sandisk Extreme Pro 2TB SSD for $30 off or the Sandisk Extreme 2TB SSD for $45 off.