BobAgi wrote: I could not get anything out of the page you linked me to...
No indication on what to do or what to enter in order to get a result...
Seriously!? Okay, using your query as an example, under What are you looking for: select Guest OS, under Product Name: select Workstation, under OS Family Name: select Windows 8 and then click Update and View Results. Look at the red arrows in the image below! 
Now how hard is that?
(Click image to enlarge.)
Is an upgrade to WS 10 from the version 8 I have already upgraded to possible?
I am assuming this is just a purchase question, as far as I know VMWare never upgrades WorkStation in place, you instead uninstall the old version and install the next.
Or do I need to buy a separate new WS 10?
I am assuming I can still use my WS 7 including installing it on new hardware if I need to.
VMware Workstation 10 is upgradable from VMware Workstation versions 8 and 9.
If you upgrade from the version 8 license, which was an upgrade license from version 7, to version 10 and not counting downgrade rights if applicable, you may only run version 10 since it was purchased through an upgrade path. Meaning unless you have separate full licenses that were not used to upgrade to another version then you cannot continue to use previous version on another system. In other words when you upgraded to 8 from 7 you're entitled to use one or the other not both and then same applies from 8 to 10, one or the other not both. If you want to continue to still use v7 then you need to purchase the full license for v10 not an upgrade.