I've borrowed a friends rock climbing harness when I installed my liner, but was thinking of buying my own. My roof isn't very steep where the chimney is, but since it's an exterior chimney, it's a long way down over the edge on my 2 story house. What do you guys use, if anything while on your roof, and where did you buy it? The safety harnesses look pretty expensive....I know, how can you put a price on safety?