What’s a good return on investment for Facebook Ads

We’ve recently started some really targeting ad campaigns on Facebook and have been really keen to find some business cases on what we can expect to see in way of a financial return.
It’s been surprisingly difficult to have someone try to quantify this information for me so I thought I would start my own discussion here for our findings.
At the end of the day we had several discussions about what it is we are trying to achieve. Some had been happy to see the likes grow but without these likes being converted to sales, I need to ask what the point is. We had boosted several of our posts and found that we were getting some good engagement with the posts and our page likes were growing but we were not seeing this translate to sales. We were not targeting our campaign enough and were using a scattered approach.
Enter the new ‘targeted’ product specific campaign. We set a very narrow range of people across Australia with a modest budget and ran the campaign for 5 days in December.  We didn’t promote an offer of sorts but landed users direct onto our home page with a promise of a 10% discount if they sign up to the VIP program. None did!
At the end of the campaign we were able to realise a return of $6 for every $1 spent in advertising which is very pleasing.
We’ll continue to work the different models and I’ll provide further insights as they become available.