Those are email services, they are not "plugins". While they probably offer plugins or widgets for their services. They send the emails. Plugins are for optin forms, ect.
It takes money to make money. If you need a hobby, something to take up your time, then by all means don't pay for things. Or if you want to test the waters and learn. But if you want to build a business and build an income online, then you need to INVEST in your business and use quality paid tools that help you achieve that.
My autoresponders are an investment and necessary tool and they pay for themselves every month and more.
Aweber is a quality service. Getresponse is another option that is a little less expensive.
On a side note, it's no secret that Mailchimp doesn't like marketers or marketing, so you could be wasting your time with that special deal.