Roast my idea: Rent, Sell, and Buy Newsletters

I created a small SAAS some time ago and stopped working on it in the meantime. Nevertheless, I have a useful 500+ people newsletter that some people were interested in borrowing for advertising or buying completely.

This gave me the idea to create a platform where people could find a newsletter that suits their ideal customer profile, and use it for marketing or acquiring it.

I understand there are platforms like Flippa and MicroAcquire, but I am wondering if there could be customers for niche market of newsletters?