InDesign CS6 was still buy-able as a standalone license, last time I checked. <click, click> Yup! The page I bookmarked at Adobe claims that you have to call in to buy CS6. CS6 doesn't run on the latest operating systems, so if your OS update has taken you all the way to Win10 or El Capitan (or Yosemite, I dunno about Win8.2) then you are out of luck and CC subscription is almost your only choice.
If you upgraded your hardware when you upgraded your OS, then probably you have enough oomph to run an OS that supports CS2 in virtualization on top of your current OS.
Just to note, you don't own any software. You purchase a License to use the software. Once you have the software license you are granted access to installation files to use the software as per the EULA.
Adobe has changed their licensing from one time purchase and use for as long as you like, to a paid subscription, either monthly or yearly.
You can purchase a Yearly license for InDesign for €294.97 - or €24.59 per month.
If I remember correctly, upgrade prices used to be circa €500.
It's relatively inexpensive to purchase InDesign for the year, €294.97 a year isn't bad.