It wasn't easy.
I remember as a high school student in 1983 buying a plastic flip-pack of two Maxell DSDD 5.25 diskettes for $10 or so, and that $10 was pretty hard to come by. Those diskettes, formatted with TRS-80 Model III TRSDOS 1.3, still read fine, too, with my catweasel. Some CDC diskettes bought at the same time (for just as much money, too!) shed oxide and end up looking like a CD that's gone through the microwave for 30 seconds on high power. And the older Tandy/Radio Shack media has lasted well, too. You can even look at the old RS catalogs of the day at
http://www.radioshackcatalogs.com/ ; a three-pack in 1983 would cost you $13.95, for TRS-80 branded single-sided certified media.
As far as formats go, PC's and Clones have it easy; there aren't that many. When you get to other systems the formats get more esoteric rather quickly.
What's always been a stumbling stone, in the non-PC world at least, is the 'density' moniker to distinguish between FM and MFM encoding; 'High Density' is MFM recorded at double the bit rate (and on the 5.25 at 360RPM versus DD's 300RPM); 'Quad Density' like used in the Tandy/TRS-80 2000's drives was DSDD 80 track for 720K (and I know the T2K isn't a 'PC Clone' but it is an MS-DOS machine nonetheless).
The DEC RX50 is fun, and those disks, as I recall, did not have hub rings, but the dual RX50 drive, again, as I recall, was pretty good about properly clamping and centering the cookie in the sleeve and drive. Those disks also have a bit of an odd format, and with the DEC Rainbow that could run its own MS-DOS on the RX50, that is somewhat on-topic.... just make sure you remember to put the bottom diskette in bottom-side-up!
And as far is 'cheaping out' on disks is concerned, I have more than a couple of flippies that are still readable. If you're not familiar with that term, that's using both sides of a diskette in single sided drives by cutting another index hole and write enable hole in the sleeve, and flipping the diskette over to use the top side. If done with real double-sided media it worked fine every time I tried it. The drives on the TRS-80 were single-sided anyway, and it saved money to use the otherwise unusable side. There are some 'dangers' we were all warned about back in the day, but with DS media I never had a problem with sleeve 'grain' or any of the other maladies everyone feared.
Of course, IBM shipped the TM100-2 double-sided drive (or equivalents) and flippies never really caught on in clone-space like they did in C64 world, Apple universe, and Tandy land.