Admittedly, my "random IP" (and box) with Hetzner comes with a cost of seven or so times per month compared to what you write. But I find it tiresome that we pretty much end up with two camps in every single e-mail thread. One that claims that self-hosting e-mail is dead and impossible in year $X and one that claims that it is not. Stating either of these absolutes is unhelpful as e-mail in year $X requires a lot of nuance.
I should end my comment by stating that I am not attempting to call you out as the worst offender and I appreciate you mentioning delivery services. Until Google started enforcing SPF or DKIM I had a nice working setup where I used a well-established, non-profit SMTP as my outgoing relay as I was scared to bits after reading so many comments about e-mail horrors on HN.