I found a guy that has a used s/s chminey liner for sale. Approx 15-18 ft long. Does not know how old it is. Also has stove connector and thats it. Wants about $300. I have not seen it yet. Seems high. How long are these things good for? If I buy it i will have to add a prob 8-10 foot piece to it since I have a 2-story chimney, plus get the cap. What do you guys think??????????????