How can I find good guest posting opportunities?

I have reached out to many blogs in my niche and all of them are asking for money, is there a way I can find "free" guest posting sites?

Have you tried these?

https://www.blackhatworld.com/seo/the-ultimate-guide-to-niched-guest-posting-crazy-ranking-for-free.1043635/

https://www.blackhatworld.com/seo/guest-posting-technique-save-money.1001092/

You can get free guest posts, but the success rate is very low. So you either have to spend a lot of efforts and time building relationships with webmasters, or just contact tens, hundreds thousands websites trying to land some "free" posts.