VMware Virtual SAN and its pricing model is now available. The pricing model is very simple and, just like the model for the hypervisor, based on CPU sockets. There is no feature, capacity or scale limit. VSAN has to be licensed on top of the hypervisor and the whole cluster has to be licensed. This implies that you have to license each host in the cluster, even when it does not have any local disks and is only part of the cluster as a VSAN Agent. A more detailed description of VSAN licensing is available here.
I've created a VSAN License Calculator. Just enter the number of hosts and sockets per host in your cluster and it will calculate the total price of all required VMware products. It also includes a license cost breakdown which shows the price for each component separately.
Your use of this Calculation Tool is at your own risk. I expressly disclaim any warranty for the Calculator.