In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Stainless exhaust pipe 8\"?
(the Metalbestos folks), offer a single-wall pipe system in stainless and AL29-4C, I believe. Selkirk is an umbrella company for Heat Fab and other system manufacturers so there is a lot to look at.
I do not think that you can buy directly on-line unless via one of their partner distributors.