Bookfunnel helps with newsletter building, extra sales, or reviews. Interestingly, I joined thinking I could use it to offer ARC reviews, but promotions for reviews is largely dead. I've never ran a review promo with them. So I use them mainly for author-sales promos. I run a monthly ad of sorts on my newsletter about similar authors writing books like my own. The challenge is to rotate sponsors because, otherwise, the same readers are looking at the same books.
"79,000"

That's expensive. Once you get over 2k subscribers it gets pricey.
I used to use StoryOrigin but they cost money now. I've set up an account at Prolific Works but it's pretty quiet--there's only a handful of promos per month. Of the available services out there, Bookfunnel's the best, imo.