Keri,To be honest, the best way to determine the value of your Smurfs is to see what other people are willing to pay for them on eBay.
Like baseball cards, Smurf PVCs can go up and down in value. Take a look at what others are paying, and you'll get a good idea.
Better yet, take a good clear picture of your Smurfs and I'll post it here - we'll see what people have to say.