Pricing:
Making a target audience - 60$ (one-time payment)
Each message sent - 0.15$
It would cost you 135$ for 500 messages which we can do in a few hours time but manually sending them would take you days. We are making your day more productive thus more profitable!
I doubt sending spam to people on LinkedIn would be a good idea. I personally would find it extremely unprofessional and would never invest in such an ICO/project that uses such services to promote their project.
I'm pretty sure this is also against the TOS of Linkedin, making it potentially fraudulent.