Validating an idea: Pre-built, updated financial models for investors?

Question

I’m working on a potential tool for real estate investors and I need your blunt, honest feedback. I’m not selling anything, and this isn't a launch—I'm just trying to learn and build something that actually solves real problems.

The idea is to create a library of pre-built, professional-grade financial models (for rental properties, flips, BRRRR, etc.) that you can instantly use. The key differentiator is that these models would be constantly updated for things like:

• Changing mortgage rate formulas and lending rules.
• New tax laws and depreciation rules.
• Integration with current data sources for things like rental comps or maintenance costs (where possible).
• New model types based on emerging strategies.

The goal is to save you the hours of building and, more importantly, maintaining your own spreadsheets.

I'd be incredibly grateful if you could help me with any of these questions:

• The Pain Point: Does manually updating your analysis spreadsheets for rule changes feel like a chore? Is there a fear of your models being outdated or inaccurate?
• The User: What kind of investor are you (e.g., beginner, own 1-2 doors, own 10+ doors)? What's your primary strategy (long-term rentals, flips, etc.)?
• The "Ideal" Model: If you could have a perfect, always-up-to-date analysis model, what would it do that your current spreadsheet doesn't?
• Pricing & Model: What would feel most fair to you?A) A one-time purchase per model (e.g., $97 for a rental model).B) A monthly subscription (~$15-30/mo) for access to the entire library and all future updates.C) A hybrid: A one-time fee for the model + a smaller optional subscription for the update service.
• A) A one-time purchase per model (e.g., $97 for a rental model).
• B) A monthly subscription (~$15-30/mo) for access to the entire library and all future updates.
• C) A hybrid: A one-time fee for the model + a smaller optional subscription for the update service.
• The Price: Realistically, what would this kind of accuracy and time-saving be worth to you per month or as a one-time fee?

• A) A one-time purchase per model (e.g., $97 for a rental model).
• B) A monthly subscription (~$15-30/mo) for access to the entire library and all future updates.
• C) A hybrid: A one-time fee for the model + a smaller optional subscription for the update service.

Thank you so much for your time. Any and all thoughts, even if it's just to say "this is a dumb idea," are welcome and incredibly helpful. Happy to answer any other questions beyond the topic of this post. Feel free to reach out.

Doug Smith · Answer

During the last crash, I left banking and myself and another couple of banking executives started buying bad loans out of banks. We then also started buying distressed property. We all three had different skill sets and used a really detailed Excel Spreadsheet to build a model. It was really, really great, but we decided to take it a step further to do exactly what you described. Someone I knew (still know) was a big-time data base designed for a large consulting firm. We also had just started our distressed debt/real estate fund. I agreed to manage his IRA (I actually still do) for free in return for him taking our model and building it out more formally. Here was the issue...we kept messing with it...constantly. Every time we did a deal, we learned something that we would want to change in the model. Today, we still use the spreadsheet (no, it's proprietary to our funds and we aren't sharing it...before anyone asks). I guess my point is this - you can almost get too granular and overthink the model. I did back in the day. From my experience/mistakes, I would create a model that hits the high-points, and then use your experience and knowledge of the specific deal to refine your "strike prices". Just my take from someone that's monkeyed with my model for 20 years.

Chris Seveney · Answer

The issue is not the models, there are tons of them out there, the issue is the data that goes into them. Garbage in = garbage out. Most do not know how to use the models to run numbers and use poor assumptions.

Koy Beck · Answer

I broadly agree with this. In practice, most bad decisions I see don’t come from missing a clever formula — they come from optimistic inputs.

You can absolutely get to a solid yes/no on a single tab if the assumptions are conservative and grounded. More complexity often just creates more room to justify a deal that shouldn’t be done.

Where I think tools can add value isn’t by adding more inputs, but by enforcing discipline — for example, conservative defaults, stress-tested scenarios, and making it harder to ignore downside cases.

The real risk with any model (spreadsheet or software) is that it gives a false sense of precision. If it doesn’t force realism on capex, opex, voids, or exit assumptions, it probably does more harm than good.

So for me, simplicity and realism beats sophistication every time.

Stuart Udis · Answer

An investor can fit everything necessary on a single tab spreadsheet. The comprehensive financial modeling does more harm than good. It's the accuracy of the inputs that matter, not the number of inputs. That's where most investors go wrong. Understated capex or opex specifically.  Secondly, the more inputs, the more opportunities an investor has to justify why the property should be purchased.

Validating an idea: Pre-built, updated financial models for investors?

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