Why? If you have done this work before or more than once you should have a pretty good idea how much time it takes to complete. I suppose if you have never done the work you might be in a bit of a jam.
I promise your prices will probably vary from others. I once was requested to submit an RFP to a city government for a web project. I was one of 4 vendors chosen to do so. The RFP was clear what the end result was to be, but not the steps to get there. I priced out my services and turned in my bid. I was the lowest bidder by far and did not get the contract! However had I got the contract being the lowest bidder wouldn't have under cut myself, at least I don't feel it did. I would still have made a fantastic amount of money. So I wouldn't worry about under cutting yourself. Price what you do work for and an amount your are happy with and then run with it.
Hopefully all of us live by some values and morals. However in this case I am not sure where it factors in outside of simply being honest and figuring out actual cost and writing it down with a fair mark up. What is considered fair might delve a bit into the ethics realm I suppose, but what is "fair" to one person may be robbery to someone else and vice versa.
[edited by: Fortune_Hunter at 11:49 pm (utc) on May 14, 2009]