Max-K, don’t bother. There is no limit on what some people would do to promote their over expensive products. Ignoring the act that we are talking about a huge price difference, you have to love the strong point he is emphasizing:
” the pins all say “Pinned via PinMarklet”. That’s a pretty important thing for me.”
What?! Are you serious?
Now, even if this wanna be plugin would be free, I still wouldn’t use it. One’s character says a lot about a product. Just imagine dealing with this guy in need of support. So yes, codecanyon and google search.
https://www.nextscripts.com/ is a decent solution, if it works well, but most of the services are covered for free by Jetpack. I would pay for google+ and pinterest.