It would appear that VMware HCI 6 Kit Essentials is no longer available directly from VMware store - potentially calling our licensing team would differ. Looks to be still available from 3rd-party sellers for ~$15-16,000 but I can't speak to the legitimacy of any I have come across.
Going by commonly quoted vSAN list prices of ~$2,500 per socket (vSAN Standard) for 2 nodes + regular Essentials Plus @~$6200 comes out about the same as the above, but with no spare node vSAN licensing (Witness comes with free license anyway). If you have a vCenter already then buying 2x vSphere Standard (~$1700 each) instead of Essentials would offer more flexibility should you wish to expand later on or integrate this cluster with other vSphere workloads without the limitations of Essentials.
In all honesty though, your best bet for accurately comparing any 2 (or more) licensing models is to call the relevant sales teams (at VMware or 3rd-party) and get quotes for both and then make a more informed decision.