What's the best way to find a UX/UI designer willing to join a project for equity?

I'm a problem solver at heart, and programming plays me like a harp. I love it, and I'm good at it, and I'm interested enough to spend hours honing my skills in it for no direct gain. I've done some web design and while the backend is usually a breeze the frontend more often than not causes me a lot of trouble. Design, user experience, making sure it runs in all the browsers and resolutions, that sort of thing. These are things I struggle with, mostly because my interests lie elsewhere. I know there are some truly excellent and amazing designers out there, though, who are the exact opposite of me.

I'm cooly aware that most people wouldn't be caught dead not getting paid for their work, but sometimes you need to build something that can generate enough interest to even attract angel style investors. That's the stage I'm at; I have some savings I can live off, but not enough to support a whole team. I've given myself a few months to build something of a prototype, and without a designer I can do it myself but it won't look its best, even though it'll be rock solid under the hood. To work with someone at such an early stage I'm willing to share equity fairly (eg equal shares, or something like slicing pie), but it would still be 100% their time, my time, and another partner who will become more involved in the business side of things when it's ready. If it's a big waste of time, the designer would have to be ok with that, as that's a part of the startup life. If the prototype (and then mvp) is successful of course the rewards will be there eventually.

How do I find or approach them? What can I offer them that they would find interesting enough to even consider such a thing? Any advice would be much appreciated.