@Brian Bradley Actually, Gary did expressly ask for an ROI calculator. "Does anyone have any recommendations for, or can send over, an ROI calculator I can use to evaluate tapes effectively?" That's where our responses came from. I do understand your point that it's hard to know where to start but I stand by my assertion that starting with someone else's is a very bad idea.
As @Nathan Turner mentioned, he and I compared our calculators. That is the very best way to get input into how yours is working and what you might be overlooking. Even after you've been doing this a while, you can learn a new twist that might make your process easier.
New investors need to build relationships in this space. Go to events and talk to other note investors. If you find a like-minded one, sit down and compare calculators. You'll both grow and learn. Bigger Pockets could be a great way to start that kind of relationship but it's probably not the best place to do the hands-on work.
Personally, I won't give my students a calculator but if they take a stab at it first, I'm happy to go over it with them and see what they've left out. They need to think the entire process through first, on their own, to understand how a deal really works and it is not helpful if I let them skip that part. It has nothing to do with not wanting to help others succeed.
Also, I wholeheartedly disagree that note investors are not open, helpful people. I've been in real estate forever and I continue to be shocked at how open note investors are to sharing ideas and resources. It does get exhausting to be peppered with the same new investor questions over and over though. Maybe you are speaking to the wrong people or somehow approaching them at the wrong time.