Thank you for the info Jon.
Yes, I have already ordered the ClusterO2 mask and regulator!
A point I had not considered re: certification. I will be sure to ask if I decide to purchase a tank/get reimbursed by my insurance. Thanks for this!
It seems that DME companies now have a flat access fee of say $130 per month to "access" their equipment. This does not include the actual oxygen content used. For every tank that is filled, there is some smaller charge (I think it was $45 for a type M tank). This is all covered by insurance, so I don't pay the full amount. Still, the cost to me is around $450 per year to "access" their equipment plus however much oxygen I get filled.
I would like to not pay for monthly rental access and have a tank sitting unused for years at a time. What I'm trying to find is a DME supplier who will sell me/my insurance a tank so that I can have one at my disposal for the first few headaches in a cluster. That will buy me enough time to get the whole rental thing with Apria, Lincare, etc. started for the rest of my cluster.