I wanted blank keycaps, but different profiles, so I ordered this set from amazon: https://www.amazon.com/gp/product/B06XK984SB. Yes, I have the remaining 20 keycaps in a box somewhere (I'm using almost all of the 1u's). For $15, most of what you're paying for is packaging/shipping/listing/overhead. The actual plastic keys themselves just aren't worth that much, so it just isn't that big of a deal if they don't get used. It feels a bit like those products on amazon where you can buy a 1 pack for $5 or a 6 pack for $6. Maybe that'd be different for a more expensive set.

There are a lot of people in this community that also do their own 3D printing, and the idea of getting hung up about making some plastic product that'll sit in a box somewhere or trashed is pretty incompatible with the hobby as you're going to end up with failed printing attempts or iterating your prints into new improved versions and not using the old version.

But if you're that concerned, especially if you want uniform profile caps, there are plenty of sites out there (like a lot of the vendors that post to this subreddit and /r/MechanicalKeyboards) that let you order them in batches of 10 or even any exact number you want.