There was a time when you could walk into any computer store (or even Walmart!) and pick up a box of ten Blank Memorex floppy disks. In case you haven’t visited Walmart in a while, those days are long gone.
Whenever I run across boxes of 5.25″ (also known as 5 1/4″) floppy disks, I always snag them. These here are single-sided, single density — sometimes known as SS/SD, or 1S/2D. Each disk stores roughly 180k worth of data per side. With a disk notcher you could also write data to the back side of the diskette, effectively doubling your storage space.
SS/SD disks were used on most pre-PC systems, including the Apple II and the Commodore 64. That’s what I use them on, anyway. Double Sided/Double Density disks could also be used on those older systems, although there is no increase of storage space for drives that can only access one side of the disk. The format most PC users are familiar with, double sided/high density (DS/HD) diskettes are the ones that stored 1.2 megabytes of data. These disks can not be reliably used on older single-sided disk drives, which is what makes SS/DD and DS/DD disks so valuable these days.
As 5 1/4″ diskettes were being phased out in favor of the (then) newer and smaller 3 1/2″ diskettes, it was not uncommon to see boxes of 10 floppies selling for $4-$5. You could get disks in bulk for much less. Ironically, $5/box for these 10 packs is now considered a decent deal, and 10 packs of floppies such as these often sell for $10 or more on eBay and other auction sites. As you can see, I enjoy picking them up. Especially the Blank Memorex disks.
If you want to hear more stories about old floppy disks, check out this old episode of my podcast, titled (unsurprisingly) “Floppy Disks.”