Generally you don't have to buy the bags from the manufacturer of a vacuum cleaner. A google search with the words Airway Centurion will probably bring up at least one website that sells the bags.

Yes, Air-Way has recently gone out of business.
What you can do is order from Air Tec. They are using one of Air-Way's models and also use Air-Way's old metal attachments. These use the same bag-size as Air-Way and Vita-Vac and will fit your Sanitizor-Centurion.

These bags are actually the same or better quality performance than Air-Way's bags. They are the meltblown material and not paper like regular generic bags.

The other option is to purchase the generic bags from any vac shop. This would be the last option though, since the performance is not as good as Air-Way or the above. They will not filter as well. You want the inside of your vacuum clean as possible and you had that with the Air-Way bags.

Go to the link and contact them.

Here is a link that might be useful: Air Tec