SD cards, SSD, USB drives, any form of computer memory really and replacement batteries too eg for cameras.
I suck up the cost and buy directly from a reputable manufacturer.
There's nothing quite as frustrating as loosing photos and footage before it's been ingested. Always use name brand media and always duplicate it asap. Ask me how I know.
It was a cousin's wedding. Fortunately I had two cards, filled the first and the second one bit the dust. The ceremony survived but most of the reception pictures are lost. Not the worst case but they were not happy with me. Mem cards were a lot smaller back then.
Agree for the expensive stuff, but started buying cheap usb sticks a few years back and yet to have one go bad. They aren't as quality as fidget toys, no moving parts, but they do the job they were made for, unless you drive over them with a car or something.