How to send more than 5000 Emails per day from Salesforce?

Dear Architects,

Polling this group to see if anyone has implemented any solution for sending more than 5000 emails from Salesforce core CRM? 

To keep it simple, all I am looking for is to send mass emails to send more than 5000 emails per day,  by selecting records from a custom object. 

Not really looking for a proper email marketing solution 

Here are the solution options that I have discovered so far. 

Solutions offered by Salesforce

1. Marketing Cloud
2. Pardot

The cost is a bit high for using these solutions, so these options are not really under consideration at this moment. 

Solutions on AppExchange

1. Mass Mailer
2. iContact - Based on my understanding of this solution, this requires a campaign to be created, which is not ideal for our use case.

Has anyone used this or any other solution from AppExchange? Will you be able to share your experience?

API Based Solutions

1. GMail API
2. Amazon Simple Email Service
3. Twilio Sendgrid

Have you used this or any other solution using APIs? Any insights on how that worked for you?

#Mass Email #Email