vSAN Evaluation is freely downloadble after registering online. Because it is embedded in the hypervisor, the free trial includes vSphere and vCenter Server. vSAN Evaluation can be installed on all commodity hardware platforms that meet the hardware requirements. vSAN Evaluation use is time-restricted (60-days). vSAN Evaluation is not for production environments.
VMware also offers a vSAN hosted hands-on lab that lets you deploy, configure and manage vSAN in a contained environment, after registering online.