I have quite a few redtailed hawk feathers as well as great horned owl feathers, but I'm afraid if I try fletching with them I am going to get bit or footed badly.
I imagine my USF&W permits would be rapidly voided as well.
On a serious note, vulture primaries would be excellent fletching because of the extraordinary stiffness of the web or vane of the feathers. They are very strong feathers, but not so much better than turkey primaries that it would be worth the extra effort and overwhelming risk. With a good quality magnifying glass and a feather identification key a Conservation Officer or USF&W agent would know within a minute whether you had legal fletching or not. If there was a question, it would go in for DNA testing and they'd have an answer right quick.
With just one Federal charge on your record you'd be branded for life. You'd never make it thru a game check again without having your vehicle tossed like a crack house bust! Is it worth it, really? Not when there are sources where you can get 100 #2 turkey primarys for as little as $25. The cost/benefit ratio just ain't there.