Yes you can buy a perpetually licensed standalone version (LR 6) the rental version is called LR CC.
B&H, Adorama, Bestbuy, and a host of other places sell the full version. At the moment, I've only found the upgrade version sold by Adobe directly as a download.
Thank you, Captain.
I was just on with Adobe. Folks who purchased Lightroom 5 in April of 2015 get the upgrade for free. Prior purchasers (me) must pay $79 for the upgrade.
Have a good one.