I've done some for a freelance client a quick spend ($15-20) for 24 hour post boost with traffic increase but no sales. Anything over 24 hours for boost or regular ads was a waste of money. Facebook seems to be the biggest bait and switch in history. Pay to get "likes" then limit your reach (down below 2% now) then paid again to reach the same people who you paid to acquire.

Email is still king. Develop an interesting, timely, helpful newsletter can have a large return vs traditional advertising. Same client I worked with spent a lot less and their return was average $2500 a month in sales. It's doesn't seem like a lot but this is their off season and they are generating revenue like in-season.