Every now and then I go posting inside Facebook like this
https://endfb.com/getting-startedThe value comes from doing this
https://endfb.com/the-battle.
You reach an increadable 1000 people per (5€) Currently I have a reach of about 380.000 people that was done in about a couple years.
Doing that is undisputed in the area of marketing and nothing can match that advertising value.
Wether and if you products are appealing for Facebook users is another question though.
It isn't easy either since you have to directly combat the Facebook moderators to get the content approved inside Facebook.
The risks are your account getting banned or directly get oppressed by them.