Ask IH: Anyone have experience serving a niche within Etsy?

I love fly fishing. A large piece of the market in the fly fishing industry is flies. Typically, you buy these at a local fly shop or online from discount sites.

I've been thinking recently that I'd love to be able to buy them direct from independent fly tiers, and after some looking around, there's a decent chunk of people offering flies on Etsy.

I'm wondering if there is an opportunity to grow a niche marketplace that addresses the needs of these buyers and sellers more specifically (filters for type of bug, season, region, color, etc.).

Does anyone have experience gauging the size of a market on Etsy? Or does anyone have experience or insight into addressing a niche market currently served by Etsy?

Thanks!