Amongst a myriad of useless fluff that's going around on medium about freelance writing....this is an excellent one carter...thanks for sharing your experience...going paid on your newsletter is a tricky decision..everyone expects newsletters to be free...if incase you want an alternative try platforms like swapstack.co and paved.com to find sponsors..they help you find relevant sponsors regardless of your audience size...ppl with even 800 subscribers are making $700-$1k a month..with a niche newsletter like yours i am sure you can find good sponsors