Independent designers, especially new ones, sometimes find estimating a job to be an intimdating experience, at least until you get the experience. We wonder how much we should ask, thinking that maybe there's a menu list of typical prices somewhere.
There are guidelines and accepted practices (thanks to such trade groups as the Graphic Artists Guild) and there are standard prices for some things but in all estimating includes not only knowing what prices are but also what you expect to do. Of course Murphy's Law enters into it, because you can budget tightly but something unpredictable can still happen
The best way to approach it would seem to be understanding it, like everything else in design, as a development process. You gather all the information you can get and it informs decisions one makes. It's not so much a menu-list as it is a set of problem-solving tactics that form a coordinated strategy.
As a budding independent myself, then, I was thrilled to find that illustrator Mark Monlux has assembled a clear and straight-ahead flash slideshow that enables the tyro to get thier head around estimating jobs. This is good stuff and can (and should) be seen here.