> There are freelance sales people that will sell your product for a fee, with the advantages of using their network and their feedback in an early stage of development
This is quite common in Europe, not sure on other areas now.
These are people that have worked as account manager and decided to start their own business. I know one that has worked for Accenture, one ex Microsoft. They work for a percentage normally and with that it is in their benefit to sell as much of your product as possible.
They have their network and knowledge, I liked working that way a lot.