Upwork: This website offers a great marketplace for selling just about any professional service. You don't need a merchant account, website of your own or anything else for that matter. All you need to do is be able to provide a high-quality service at a reasonable price. But be informed, you will have to compete with many others that are constantly bidding on open jobs.
If you're looking to address some immediate financial needs, then the app economy is likely right for you. Thanks to the global sharing phenomenon, launched in part by our smartphones and ever-burgeoning global connectivity, you could easily opt for some quick active income by using well-known apps. From ride sharing to deliveries and even quick tasks, there's an app for that today, as the saying goes.
If you have pop-ups and optins on every page, I would have to think that it would be a lot harder to convince someone to link to it. Especially since the pages where you have your optins (and probably receive the most traffic) are probably the same pages that you have your best content on as well that you'd be hoping to pitch in your outreach campaign.