The ev9d9 arm is going to be difficult, but they do pop up from time to time. Be prepared to wait a while. The amanaman is going to be next to impossible. If you’re just wanting it for display, I’d suggest stealing an arm from a Stan Solo replica. Just be sure to disclose that if you ever sell it.
Toy Poloi has a cool video on YouTube where he takes an arm from a modern ev9d9 and repainted it to match a vintage one for display.