In reply to gcandlin: Facebook ads, I've used a few times, but as a Facebook Social user they annoy the hell out of me and I'm inclined to think that Facebook has had its day regarding PR/Advertising use... So I would hesitate to advise the PPC scheme in its current form.
Goggle Ad's is different and set up correctly can work very well, currently spending up to £30/day over about 100 ad's and a couple of thousand key words and its generating reasonable conversions. So no complaints so far. It does take a lot of time to set up correctly through, takes time monitoring and tweaking each add, some will work some won't.
I guess it boils down to the amount of time you can afford to spend on building a successful Ad campaign against the expected return. Also the kind of business you are in, you likely buyers, social pattens etc...