I've found that streamers tend to have pretty nice merch. Unfortunately it tends to be pretty expensive because of special requirements and fairly small production runs. They also interact with the viewers directly, so complaints likely come up on stream.
It seems like Youtubers on the other hand just send a picture to a merch producer and let them deal with it.
Custom T-shirts with extremely limited runs (hundreds) cost $10. Creators are selling them for $20+. Creator merch is a scam or if you want to look at it more positively, a donation with an item in return but no items sold by a creator is even close to a reasonable profit margin.
Buying for $10 and selling for $20 is pretty reasonable. You do realize there are other costs than just material right? They aren’t taking home $10 on every sale.
You can do t-shirts for $10 with even smaller runs than that. I've done batches of 50 or less at $10 a pop going with a local screenprinter. This is usually 1 or 2 colors.
20 bucks is more than reasonable for a 10 dollar shirt imo. But where I am, often these shirts will go for the equivalent US$50 plus the same or more in shipping. I think that's a scam. 20 bucks is nothing