Don't get me wrong selling and getting real product validation is the best.
But emails are one of the most valuable resource for marketing. You can always email people. But even advertising to the people that liked your page will cost you money and will be competing with tons of information.
We actually went through some influencers on our side (known fighters or coaches).
It definitely helped gain a lot of credibility on our end because if it was that much of a revolutionary product, why would pro athletes not use it amd endorse it. so for us it helped a lot convince our customers that it was a legit product.
However, we have been offered to post on a few famous people pages for 5k but we didn't do it as we thought it would actually be seen as paid advertising instead of genuine and authentic love for the product. We're still exploring those avenues though.
We created a lot of content and spread it guerilla way aka bombarding facebook groups that were relevant. On the other hand we through all of our network as word of month is still one of the best way to market your company.
No we did not see it had much of an impact. But what we saw had the biggest impact is our website! We refined it a lot based on customer interviews to make sure to convey the worth of the product (which was lacking in the previous version). Also customers had a lot of questions, which is not good for sales. As soon as we put the new website up, sales increased!
Build an email list! And try to pump up the subscriptions with different sales channels - you'll be able to know which ones work best for your business before launching your campaign