Building product models is an art, not talking about building prototypes but building financial models. Modeling is a product managers domain not the CFO. The finance guys are your best friends in this and have skills you do not need to command however you have functional knowledge they will never grasp.
How do you know costs cross functionally if you do not walk through every step from raw material sourcing through sales and support? There are a few things that are often missing from models: Development costs and Redevelopment costs! New features also will eventually lead to new platform requirements as will expansion.
Recently I was reviewing a services firm model and while there was cost inserted for new staff and ramp loss to productivity there was no cost expansion on services for that new staff. Not the payroll overhead but the support.
Productivity is critical in early stages of an offering, my base is model to 75% of productive not any higher. We all ebb and flow as reflected in output then there is change that stops it all. Once the service grows the economies of scale allow you to raise that to 85% or better but I suggest sand bagging you numbers.
Product managers excel when they learn not to fight change, modeling needs to embrace change. When you are building a lifecycle model and the curve is up then plat only you are not doing your work. Weighting a lifecycle model requires you to embrace change including all of the implied and embedded costs of new features, platforms. re designs that go with growing and sun setting your product.
Mining companies include closing and clean up then a few lawsuits. Are you that complete?