+1 for Buttondown from me as well, but I don’t have that over 1000 subscribers “problem” quite yet, so there’s that
Beehiv has free plan up to 2500 subscribers, but might be bit overkill. Haven’t tried it myself either, just heard it recommended a few times.
Sendy is something I would personally try if I ever go over that 1000 subscribers limit and decided not to use Buttondown anymore. It has a one-time fee of $69 and it uses Amazon SES for sending emails. The sending of emails itself cost almost nothing, as far as I know, it’s a dollar per 10,000 emails or so.
The caveat with Sendy is, that it’s a self-hosted app, so you need to install it on a server. Digital Ocean would be one hosting option for that. Here’s a guide for that if someone wants to give it a go. Installing and configuring is not rocket science, but there’s some configuring involved surely
Then there’s MailChimp of course, seems to be about $26.50/month per for 1500 subscibers. But their pricing go up pretty fast from there.
Let us know if you find some great alternative(s) for Buttondown. Would be curious to know myself!