This document outlines a range of technical options and estimated costs of each.
Technical projects by nature are notoriously hard to cost because by nature each one is breaking new ground and risks are hard to calculate. For projects to work to a predetermined budget, the technical risk must be priced in from the beginning and this takes the form of high salaries for developers to meet specific technical goals. There are many mIf the goals are softer, if some corners can be cut, if some features are considered optional - i.e. included only if the essential things are completed.
The below...