When I first was doing woodstoves back in the late '70s, real good flue pipe was over $2 an inch! Be sure to use all stainless pipe. I like the insulated pipe like the metalbestos stuff. I see the price has gone up a bit ($7 per inch-ouch). Still, anything but stainless will rust out faster than an old Fiat. At these prices, I would really shop around for awhile for price. If you are going any real height, it gets so painful brick starts to look good.