POLL: people from my other sites to sign into my una

I know I asked this before, but I need a way for people from my other sites to sign into my una using sso. I have members all over the place on different wordpress sites and I need to let them sign into a single UNA from the other sites. Can anyone make this work? I know UNA has oauth, but people can't sign into UNA with it from wordpress, right?

I can pay about $200 for this right now if someone can do it. How much would it cost?