I never did call linde. KMS is more than oxy pro. I heard through the grapevine renting is $10/month per tank. So that's the same as praxair.
I did come up with one idea after talking to
@Alexander . He reports propane with a bigger tip works nearly as well and then all you need is an oxygen tank. A propane tank is cheap. So that option might cost $300 for a 110 ft oxygen tank filled from oxypro. I've got a good propane regulator and a propane tank already. Still more than I hoped to spend but .....
Looking online it's far less in places like LA. $200USD for two tanks filled. So why is it doubleish in Canada?