Did anyone do marketing deals for an ecommerce site?

Hi all,

I have had some success with a Shopify POD store. The idea was simple, selling updated old maps of villages, cities and towns. It is in Dutch @ https://www.vintagestadskaart.nl/.
I automated the image processing and clean-up part, made a connection to a local printing company, and everything has worked well since.
However, marketing is a complete mess. Since the beginning, I have used FB ads with some success. The Return-on-Investment was 3-5, netting a few thousand € in revenue a month. However, I have few returning customers, and almost no people finding the site by other means 😔.
Also, FB ad success has gone down, so it is not really profitable anymore...

I have also lost all motivation to do social media posts/ blogs, etc. So as of now, it's quite dead...☠️ . It's a shame. I also have shiny new projects to do, so limited time for this store...

I was thinking of either selling the site (but as I have very low revenue numbers now, the value will be very suppressed). Or alternatively, maybe strike a deal with a marketing person for a revenue cut. Has anyone had success with such an arrangement, and how did you go about doing this?

Thanks for your ideas!!
Jasper