Contacting chrome extension owners for data sharing coop

So basically I need to get chrome extension owners on appointments to discuss a data licensing agreement. I had my VA compile a list of 20 emails to start, but i'm wondering whats the best way to reach out to them to ensure the following:

1. I don't sound like i am trying to sell something (i'm not, in fact it's the opposite since i want to buy data)
2. They open the email
3. they understand I want to buy their chrome extensions data

ideas:
investment inquiry
just put in the headline, i would like to make a purchase order
just say "data coop purchase" in headline

How much are you willing to offer them for the data?

Maybe try asking them if they're looking to monetize their plugin in the subject line already?