Kristine-
I have a little experiance with facebook ads. I ran a free facebook ad a few months ago while they were offering a special to small businessess new to facebook advertising.
In less then a week, I tripled my facebook fans from 200 some to now just over 600. I have noticed that since the ad ran I will just get random new fans People I don't know and that don't sell one etsy will randomly like me.
While the ad was running it increased views to my shop. But, none of those views resulted in sells. I think the ads are a good way to get your name out there. I figure the more facebook fans the more people seeing my work when I post new work and thus this will result in more views on etsy and thus more sells.
Right now, I am running a $75 ad on google ad words. It is also a free promotion if anyone wants to take advantage of it. And, honestly I have not noticed an increase in views in my shop. But, I only have a $5 a day budget. So, it is still early and I will wait and see.
I would love to hear what othes think about google ad words as well as facebook.