My $.02 in regards to reinventing the wheel. I am by no means an expert so take my advice with a grain of salt. I think that if you are proficient with excel (not even proficient, literally just capable) I would build the model yourself. Really will comprise only a couple main sections (for lack of a better term). You're looking at income (gross from all sources) less any vacancy and bad debt. Then, net off all operating expenses (not including financing) to get your NOI. This is a great exercise as it gets you thinking about all the types of expenses (ie. will there be a prop. manager, what will you allocate for repairs and maintenance, cap ex, utilities, etc. Are you in a region where snow removal may be necessary? Always going to have taxes and insurance, although perhaps some of these can be downloaded to tenant) By playing/inputting these numbers, and building the spreadsheet yourself it shows exactly how each one affects your bottom line, and therefore your value. Apply a CAP rate to your NOI to estimate value. Buy doing this, you can see how great small amounts in NOI reflect big swings in value. Also drives home relationship between NOI and value. Finally, will make you really analyze your debt service, as what is left over in NOI goes towards the mortgage. By doing it yourself, you are much closer to mastery (I think the final test of mastery is teaching someone else) and I think falls somewhere in line with the the old "catch a man a fish..." lesson. It may be painful at first, but in all honesty, I think you could have something really workable and usable within a couple hours. This is the approach I would advocate, more for the fact it gets you into the weeds. That's where the value is.
Best of luck!
-Tyler
