.02 cents a pound is a little low. I think its like $120 a ton which is about .06 cents a pound. I wouldn't worry about overcharging someone. He wants a set price. If he doesn't want you to work by the hour(which I wouldn't do anyways) then its fair game. The only question would be, is the guy gonna get other estimates. I think what you are charging them is fair. I would probably charge a bit less but I have pretty extensive carpentry experience(licensed in the state of MA) with the tools and knowledge to complete the job effieciently. It is tough to say exactly with just your description exactly how long it would take me. All I am picturing is a 300 square foot one story shed(empty I would assume). If that were the case that would be a half day job and probably 150-170 to dump. This is kind of a shot in the dark and for you it really depends on where you are dumping and what they charge. I wouldn't have to rent anything. If you were gonna rent a trailer you might be better off with a 15 yard dumpster. Around here you can get one for $300. No rental fees no trips to a dump. Rip the thing down and tell them to come get it. I seriously would be cleaned up and outta there in 4 hours with two other guys for sure. Provided at least one of them could use a sawzall and has some knowledge. I would say bid a little on the high so you can take your time and do a good job without getting hurt or anything. Start on the roof and work down. Or just plow it over with the bobcat and cut it up. What is the sheathing on the building? You might have to cut the rafters away from the ridge and cut the ceiling joists out. then the bobcat will definitely push it right over. just be careful when cutting the rafters and ceiling joists. Use common sense.