Also, how long is your investment horizon? Is it really that important to you to project out to 30 years or is 3λ years sufficient along with a terminal value that represents the expected NPV beyond 5 years? Usually this latter approach works best and looks the most credible to potential investors. There are numerous ways to calculate terminal value including multiples, current market values projected forward, and round guesstimates. Obviously these decisions are affected by your personal preference and the type of investment for which you're calculating present value.
I never have to reinvent the wheel. And as a professional accountant, you can imagine how many different "wheels" I use every day! Profit & Loss statements, Balance Sheets, Cash Flow Forecasts, Time Sheets, Break_Even Analyses, Margin Calculations, Business Plans, etc, etc. When using your own prior work as a financial template, you get another benefit _ you are so familiar with the template that it takes you no time to figure out how to use it. And each time you refine it just a little bit more. So pretty soon your templates run like a Swiss watch! All the bugs have been worked out, you have tested it with many different clients and many different business scenarios and you know you have something you can depend on. Financial Templates as Tools _ For someone who is not a finance professional, financial templates serve a slightly different purpose. They still save time, of course, but they also provide a tool that person would have to pay someone else to develop.