I bought ten small microSD cards, 32 GB, for 3 EUR each. Very likely they're counterfeits. But they did come in a small plastic case. You could reuse these for mail. They also all come with an adapter. I have tons of these adapters, usually throw them away.
As for the article, it mentions:
> It is normally recommended to use bubble wrap to protect SD cards in transit, but I have never seen bubble wrap inside a normal envelope which made me suspect that this would elevate the rate of delivery failure.
Bubble wrap envelopes exist, obviously. The envelopes are a bit larger but would work. When I order small items from Ali, this is often the packaging they used.
I don't understand why they sell them as counterfeits. I just want 3 EUR cards, I'm not fussed about the size (they're for things that need a few MB, usually). However, nobody will sell me cheap cards, unless they're counterfeits that claim to be 32 GB but are actually 16 GB instead.
You can get “genuine no-name” cards at that sort of price, though I can't testify to the long-term reliability. Some that I have on use are https://www.amazon.co.uk/gp/product/B09YGV2JGP/ which are £2.50 each if you get the 10x 16GB option. I got a 5-pack a larger version for a Thing a short while back and the ones I've used thus far fully checked out to support the claimed storage (I don't trust cheap SD cards without verifying, because of the counterfeit issue and quality issues, so ran a full test on each) and have so far maintained reasonable performance.
That is why there aren't genuine smaller cards: there just isn't a large market for them because the parts availability means the smaller capacity cards wouldn't work out any cheaper to source, so any noticeable drop in price would be through the seller reducing their markup. For the same price, people will buy the larger ones for the same price just-in-case they need more space later because why not? Even if there is a small price difference, if 8Gb or less is pennies cheaper than 16Gb or more, people will generally go for the larger option.
So to “why sell counterfeits?”: the scammy sellers can't sell them honestly in enough quantity to be worth bothering, so they lie.
As for the article, it mentions:
> It is normally recommended to use bubble wrap to protect SD cards in transit, but I have never seen bubble wrap inside a normal envelope which made me suspect that this would elevate the rate of delivery failure.
Bubble wrap envelopes exist, obviously. The envelopes are a bit larger but would work. When I order small items from Ali, this is often the packaging they used.