The best means to self publish are actually either:
- Put your comic on Webtoon and Tapas and try to build an audience.
or
- Get it printed from a printing firm (one in your own country is usually best) and then sell copies online in an online shop or Etsy or similar and take it to comics events to sell.
Anything where the publisher isn't paying you, but you're paying them is a scam. It's called "vanity publishing" and it's almost never worth it because you're handing your work to a publisher that has no stake in your work selling, because they've already been paid, so they will barely put work into marketing and distribution if at all.
If you're going to pitch to a publisher, get yourself an agent who represents similar sorts of creators to you and start pitching to print publishers who publish similar sorts of things to what you're making. For example, look into who published other print editions of popular webcomics. Most of the ones that aren't absolutely massive it literally was just the creator running a kickstarter, getting it printed and selling it themselves though.