Value is tough to determine on the Wilkins and Wontkins hand puppet set. Mainly because they're pretty rare and don't pop-up too often, but the fact that not a great deal of people even know about them factors in as well. However, people who are looking for something them are generally willing to pay a good price.
From what I can garner, a set of Wilkins and Wontkins hand puppets in mint condition would probably be worth in the neighborhood of $800 or so given todays market and desirability of the puppets. However, any damage at all will effect the price quite a bit. Even a tiny hole is significant to a serious collector and generally, serious collectors are the only ones who'll be willing and able to front the cash for something as rare as these puppets. Considering the hole in the back of the head on yours, I'd venture to say the set would be worth in the $400-$500 range.
Actually getting the amount could prove tricky these days though. Wilkins and Wontkins aren't exactly well known by today's collectors and, most importantly, the market is pretty dire right now. So, it's hard to say for sure how much they'd be worth today, but $400-$500 sounds pretty right to me.