Medicare B is not likely to cover it unless it is paired with something else like albuterol. I e never figured out how to yet.

In a pinch, without a prescription, Amazon:
https://www.amazon.com/gp/product/B0B32MJLZN/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
I fill my prescriptions at CVS, the first time they rang it up at the insurance Part D rate, so I called and said skip insurance, use GoodRX and that would have been great, but then they found an even better rate. I last paid $6.16 for 90 vials.