If you setup a domain to use Cloudflare, and then sign up for their zero trust system, you can get a code to get up to 4 yuibkey's for $10 each.
I came across this blog post about a similar offer: https://blog.cloudflare.com/making-phishing-defense-seamless...
but it now states:
> UPDATE: This offer expired on January 3rd, 2023 at 8am PST.