Edit: Oops, can't update links on this post anymore. Will make changes to the site.
Edit 2: Ok just updated the site - no longer need to enter your email to access the list. Hope this post gets restored to the Show HN page as can be very useful for first time founders :)
Most of my sponsors are inbound through the newsletter and from referrals, I haven't done any outreach so far but plan to do this in the future. Lots of resources for rates though, easiest is a flat rate or charge CPM per send.
I run https://www.startups.fyi and feature profitable startups/side-projects along with revenue info (a lot of them are from solo-founders like yourself).
Edit: Oops, can't update links on this post anymore. Will make changes to the site.
Edit 2: Ok just updated the site - no longer need to enter your email to access the list. Hope this post gets restored to the Show HN page as can be very useful for first time founders :)