We've been looking at it carefully. Facebook gets $150 a month from us and according to Google Analytics, accounts for 3% of our pageviews. I was able to nurse us up to the front page through pure organic search legwork (our SEO was limited to making sure we passed Google's mobile qualifications and their general "you're not a spammer" worksheet).
It's honestly not that hard. The problem is if you look online, the general attitude of SEO is "you must practice the Black Arts exactly as I say or you will sink into the mire! spammit spammit spammit! Subscribe to my newsletter!" My needs won't parallel yours as mine are for a brick'n'mortar for-profit with one location but my needs were pretty easily met simply by abiding by Google's tools. Of the evil wizards, Neil Patel is the least annoying and most pragmatic.