Just to second 's suggestion, if this is for non production use, then the VMUG Advantage Program is the way to go. You can get 1 year subscription for $210 which will give you access to a whole bunch of software not just ESXi on 365 day licences. You also get a slight discount if you buy 3 years.
If it is for Production use, then there are 4 options available, the cheapest of which is $800 per year for 1 server, see below
- VVEP (vSphere Essentials Plus) - 96 core pack. Maximum 3 hosts, $35 dollars per core. includes vCenter - Cost=$3360
- VVS (VMware vSphere Standard) - $50 per core (charged at minimum 16 cores per socket). Includes vCenter. Cost of 1 host with 16 cores or less = $800 per year
- VVF (VMware vSphere Foundation) - $150 per core. See William Lams VVF vs VCF article for what's included. Cost variable
- VCF (VMware Cloud Foundation) - $350 per core. See William Lams VVF vs VCF article for what's included. cost variable