New to B2B Cold Emailing. What are some solid cost effect stacks?

I currently have amazon ses so I was thinking of signing up for mailwizz. I have tried Brevo, Mailerlite, Mailchimp, and Email Octopus. Email Octopus seemed to be the best value. But i have a large list of contacts to send 1-3 emails each per month. Also, I would want to give my employees their own user account. Mailwizz seems to hit that with unlimited subscribers, sends and users for a one time fee as I prefer not to have subscription models. I believe Mailwizz also has a rest api that i can integrate with the backend of my website to automatically sync lists but I am not sure.

My goal is to create a master list of 6-10000 verified emails that i can then filter into their respective groups and then blast those at a steady rate with a somewhat customized copy. Hi {{Name}}, etc.

I have used Apollo, Hunter, instantly, and other tools. Ill pay a subscription temporarily to just fill up my list but then I will cancel. My DNS is set up well and I see Apollo has an MCP with claude so i could just run some prompts to find the right within a particular company with a specific title then add them to the list. I was thinking on then verifying that with Growthtoolkit.io since its pay as you go so i would verify everything i did with Apollo once then thats it.

Is this a solid cost-efficient flow or is there something else I am missing?
Thank you for your input!