You may still be able to buy it at some department stores like Best Buy or Staples places like that. You might also want to try some college book stores. That is where I purchased mine initially. Hope that helps
To clarify a common myth, you don't need to be on-line to use Creative Cloud products. These products install on your desktop just like perpetually licensed software did. You only need to be online when downloading, installing and updating software. And about once every 30-60 days you may need to go online for 60 seconds while Adobe confirms your subscription/license is current. That's all.
You can buy the permanent license Photoshop CS6 from Adobe.
Creative Suite 6 Select Photoshop CS6 or CS6 Extended and click on "Buy".
Correct. When you click on Buy, you'll be presented with the options you want, including Full or Upgrade version: