How do you hire freelancers for single components?

It seems like most of the "quality" freelancing sites like Toptal are really focused on staff-augmentation or spending months to build out a full MVP.

I've been bashing my head for a couple weeks trying to build a particular complex React component and would like to hire a freelancer to do it. I imagine a professional dev could knock this out in a week, maybe even a few days.

How do you go about hiring someone for a single, small piece of a project?