I told him I couldn't give fair price sight unseen and asked if we could coordinate with their property manager to view the property.

Factor in how much principle they would have paid off the loan and subtract that from the current market value of the home. 

The knowledge needed is real estate principles, real estate law, and real estate finance.

^^this^^ apprx 70% gdp  consumerism, money printing, short sighted policies, what could possibly go wrong lol

OP doesn't have to do what I said, by any means, but I think she should understand the principles behind it and take action on her own--these principles are guiding in a better direction than anything anyone else has offered.Some of your points have been valid, but the part about rent and appreciation not outpacing inflation is, plainly, hogwash.

Rock solid rental while the money is in the stocks doing double duty as the principle investment as well as your down payment equivalent.  

But I have been looking into splitting the duplex into two condos (yes I know it is a lot of work) and I could probably get 325-350k for each, netting me 650-700k.Number:* Mortgage interest 2.5%* Mortgage principle 240k* PITI $2100/month* Rent 2200/month (current tenant on a two year lease)* Potential rent on my side $2400/month * 100k HELOC at 11% (fixed) (not currently being used)* est additional cost to split the dueplex 75-100k (conservative, probably less)     *new siding 30k (just put on a new roof this year)     *legal 10-15k     *fire proofing 15k     * 15-40k for stuff I am not aware of or underestimated on* some of the appreciation is external from the home     *big grocery store put in 3min away     * newly paved road in front of my house     *a building that was falling down across the street has been torn down          * Still a vacant lot with the foundation exposed and fencing around it (so more local improvements are on the way)Part of me wants to take the money and run but man I love that 2.5% interest rate and the $2000/month cash flow (including taxes and capx)I have thought about 1031 exchanging into more rentals, but I would like to pivot into storage units.

Generally, you pursue the first one out of principle and apply the learning to subsequent cases.

Although many markets have seen significant run ups in prices, many of these markets are now only at, or sightly higher than their 2006 levels. 

You could get a new loan, pay 20% down (80k), and 7% interest on the remaining 320k balance, and that would cost you $2,129 per month (principle and interest).