Facebook doesn't seem to work too well, and adwords felt like a black hole. And besides these methods seem to require experienced consultants to run an effective campaign.
I have seen dozens of business start off this way and than eventually become enterprise only platforms or worse, programmatic advertising providers marking up CPMs by ridiculous ripoff margins.
(see: boost media, dispop, etc...)
That's why we built Hits Analytics (http://hitsanalytics.com) specifically to tackle this problem. All you need to do is set the budget and pick a segment of product(s) you wish to promote, and we will automatically create and track Facebook ad campaigns for them (we do the "heavylifting" of optimizing the campaign behind the scenes based on the conversions we are tracking)
I know Amazon tried to solve it but failed, I guess a few of those deal sites too are trying. Right now the only true contender i guess is something like graigslist?