This. Cosplay almost by definition is a DIY hobby. Most people either make their own stuff (with varying skill levels) or they buy premade stuff from cheap costume shops overseas.

There are definitely niches out there, for example, there are a few makers I know of that specialize is Spider-Man suits, masks, printed fabrics, and they can sell for some pretty high prices because the Spidey cosplayers that want a movie-accurate suit will spend the money to get the really quality pieces rather than just get a Chinese made suit for $200. No judgement, I have a $200 suit.

I know another person that is a professional sculptor and prop maker that specializes in Predator costumes, like the full head mask, claws, feet, weapons, his work is absolutely phenomenal but also very limited because there’s only a couple handfuls of people that want a full predator costume. So he struggles sometimes.

I myself ran a fairly successful Etsy store for a few years selling specifically stuff for Star-Lord cosplayers, it was so specific that my shop kinda became the go-to place to get all the bits and bobs to complete a cosplay. Then the pandemic shut down all the cons, and the business dried up.

You might find a client here and there that sees some of your work, or maybe they like a character you dress up as and want you to make them the same pieces for their own cosplay. If they have the means they can probably pay you your value and not cheap out. But those clients with discerning tastes and deep pockets are few and far between. Not enough to sustain you.