Maybe try getting some banners up on cosplay/ren faire websites? Are you cross posting your work to DeviantArt, Elfwood, or any of the other "fantasy" galleries that are out there? Tumblr has become a pretty big place to market unique clothing/costumes as well, and you can always just copy/paste your descriptions off of the Etsy listings.
I agree with other posters, it wouldn't hurt to try selling just the wings individually. Sometimes it's a blow to artistic pride to break up perfect costume sets as we see them in our heads, but consumers are more and more building their own stuff out of components, rather than buying sets of stuff. It ends up costing them more in the end (and benefiting us!), but the perception is that sets have a premium on them. Weirdly, they're looking at a 'set' as more expensive, even in this case where the price is lower than it feels like it should be -
At the same time, I'm also echoing to raise your prices. Timing yourself while you work is a really helpful way to measure how much of yourself you're giving to each project, and then you can dial in the pricing to somewhere you feel fairly compensated.
Also a suggestion: Maybe try buying a few off-the-shelf hooded sweatshirts and put these wings on them, sell for both kids and adults. I bet the goth/fairy people would eat them up, and it's warm clothes/hoodie weather right now. Good luck!