Hey there!
I can build you a small Chrome browser extension which can grab all emails from the current page. Also it could put commas between if needed, some of the mailing apps require that. As the goal is to keep it simple the extension can be just as a button, each time you click it could collect all emails found on the page, format them and copy them to clipboard. If you want it on Mozilla, too we can add additional milestone, but it's better to discuss that on the chat. If you're interested to work with me contact me there.
Best Regards,
Vanyo Vanev
Senior C# .NET Developer