Feeling Fantastic in Florence

I agree that most projects can sprout unforeseables as you work through them. But this doesn't preclude the fact that many aspects can be itemised and assigned an amount of time: server set up, install your favourite cms, plan the structure, design the UI, etc. The greater your experience the better you'll be able to cost it effectively from the onset.

Infact, often by just meeting the client and hearing out their requirements and knowing what you're likely to do for them, you can imagine a rough estimate on the spot.

The trouble starts if the client or you allow for scope creep to set in: adding extra parts of functionality that weren't specified, or bowing down to an endless reiterative design process. That's where you need to be tough to deliver.

I much favour a combination of the two payment structures. One where you translate the client's requirements into a tech spech sheet with job quote and a fixed figure, combined with an hourly rate structure for the unforeseables and client whims.

There's a fantastic article on the subject over on stacktrace.it