What Makes Stained Glass Valuable?

Hi all, I’ve always been fascinated by stained glass and how light passing through color can transform a space. I understand its value comes from craftsmanship, design, and materials, but I’m still learning how to tell a handmade piece from something mass-produced.

I’m planning to install 18x24 inch panels above my desk in my study area, where I spend most mornings working and reading. I’ve looked at Etsy, eBay, and Alibaba, comparing styles and prices, but it’s hard to judge which pieces show real craftsmanship.

Has anyone done this before? How do you evaluate quality and find pieces that are both well-made and reasonably priced? Any advice would be really appreciated.