I did this with a few people at work. It seems as if the ad is not served at all if the target population isn't over some threshold. I was not able to target 2-3 people, but was able to target 30.
I put in an ad for my wife around Valentine's day and specifically targeted it to her (it helps that she's the only Memphis-area fan of a fan page I run). She saw it early on the first day of the ad window. I think setting my cost per click at the high end of the range was important.
It wound up costing less than a dollar for the successful campaign.
It wound up costing less than a dollar for the successful campaign.