The Variable Cost
Work done to create a Project Specification is normally charged on an hourly basis and is therefore an unknown cost until it is completed.
Although variable, the cost and time involved in producing the Project Specification should be small in comparison to the overall project and will reduce more major costs in the overall project.
Once paid for, the Project Specification documents become your property. You are then at liberty to take these to or your in-house programmers or any software development resource you choose.
The Fixed Cost
A fixed price quotation and timetable for implementation can be produced once the Project Specification been agreed and accepted and signed by you.
Cost generally increase with
Conversely the larger the project the lower cost per susbsystem due to economy of scale
Implementation can begin if and when you accept the quote.