Why are Woodland/Coyote M81 vests so expensive?

I was window shopping cuz I don't have funds rn, and I've looked everywhere, Ebay, Etsy, Facebook MP, local milsurp shops, and they're nowhere to be seen, and when I do find them, they have no kevlar, or they're 500 bucks, OR they're 500 WITH NO KEVLAR, but somehow people find ones for like 50 bucks SOMETIMES WITH SOLID PLATES.