As mentioned, a couple things are for sure:
- There ISN'T a magic equation for calculating an ARV... this is mainly dictated by your local market. For instance, the adjustment value of a bedroom/bathroom scheme in one market isn't the same as another. This is where you have to mainly learn your market
- It's the most wise to use SOLD properties as opposed to LISTED properties. However, I, myself, typically look at listed properties to get an accurate understanding of how long a property has been on the market before it sold at a particular price. You could have a comp that sold for $200k and a comp that has sold for $150k, with the latter being sold in 2-3 weeks, and the preceding being on the market for 6 months (overpriced??)
- Best individuals I have found to get an understanding of the adjustment prices could be other investors at your local REIA meet up, fellow real estate agent, appraiser, etc. The market is ever-changing and so, although to me, it seems the adjusting numbers don't fluctuate dramatically, they could change with passing time.
Just a few pieces of input I wanted to put out there.
Good luck in your ventures.