In high school I bought a hole puncher for single sided 3.5" disks which turned them into two sided disks and you only needed to buy the cheaper ones.
Also, there was some kind of formatting that I remember doing that make them several kilobytes larger...I think the standard was like 1.44 megs or something, and if you formatted them this special way, you'd get like 1.45 or 1.5 or something...can't remember.
And if you defraged them you could squeeze a few more files on them. But you were still always running out of space, so you had to jot done the blank space available on them and the smallest file size, and if you could find a file that would fit in the blank space of another disk, you just freed up several more kilobytes!
So you had to have boxes of these things to be able to store anything...but they were soooo much better than 5.25" disks.
Thank god computers have advanced beyond this. I now have an old 4 gig USB drive that is probably larger then the combined size of all the 3.5" disks I ever owned.