We are in VBS this week - we run ours in the evenings: Sunday - Thursday.
Each year we receive calls from parents wanting to know the charge. Several churches in our community charge a fee for VBS, we do not. I speaking to other pastors, they do so in order to help with the costs (our VBS typically costs us $10-12 per child), but also to discourage what they perceive to be the problem of children attending several VBS programs over the summer as a kind of day care. We don't consider that a problem.
Does your church charge for VBS? Do other churches in your community charge?