A possible cost effective software solution is to use a technique that combines extreme programming concept and rational unified process methods. This gives the opportunity to emphasize business results already at an early beginning, before taking an incremental step in the process.
A very first step can be defined by showing something concrete to building the product with the necessary testing and revision aimed at yielding results and keeping track/status of project. This can be done by using iterations within each phase of the project (from pre-inception to transition). Each iteration expresses a percentage of work to be accomplished and an outcome (deliverables).
Most important, this gives the opportunity to start in a simple and agile way, building something real that works, and then try to fit it into a structure "the big picture"designed for further code building, rather than doing everything at once, such as designing an exhaustive structure at the very beginning, after a thorough and time-consuming analysis (a mistake here will cost heavily).
This example approach is an abstract of a cost effective solution. The potential end-user/client will have visibility of results each step of the way and is able to measure its satisfaction.