It all comes to how much time is going to be spent there.
I think the estimater has to be or have been a climber.
When looking at a removal, I piece the thing out in my mind. Look to see if it can be felled, look to see what can be dropped and what has to be lowered and where are my lowering points. I figure up my time. I pride myself in being very accurate on removal times, usually in the summer, I find that I'm right on with my time estimate or only a half hour off (and this is with big or multiple removals).
Placement of the tree, front/back all goes into time too.
I have an hourly price I keep to myself, for one climber and one groundman or one climber and two groundmen, etc...
Also, if I use special equipment, like a skidloader to remove logs from a backyard, I have a price for that also.
Then if you use a crane, you have to figure up what their bill will be (if you don't have your own), if you have your own, figure up close to what a crane service would be.
Guys that just take a quick look of the size of the tree and make an estimate from that, without piecing it out in their mind is stupid I think.
Also, I don't understand guys putting in a scare factor higher price. If they are scared and are unsure about doing it, don't even bid. What, a $1000 price jack-up is going to mean anything if you are dead or paralyzed cause it was out of your league. But your higher bids, do make me look better, so go ahead.
Also I have noticed that if it's a backyard tree that they can't get a bucket truck to and your crew is good at climbing and rigging, you can risk to be on the higher side (price wise) cause the other companies that rutinely use bucket trucks tend to be really high on those trees.