I use Apria in central WI. There are offices in MN and WI. https://www.apria.com/locations . Funtimes and CHfather offer good advice concerning building a relationship with your O2 provider. I believe I got lucky as the Dist. center manager understood the importance of O2 for CH.
I have a credit card on file with Apria and self-pay $25 per M-tank. During the height of my cycle this year I was picking up 4 or 5 tanks every 8 days. There was never any questions about the amount of O2 I used nor were there any suggestions about a concentrator. I would let the mngr know my anticipated O2 needs prior to his twice-monthly order and, would call a day or 2 ahead of actual pickup.
Hope this helps.