I told the listing agent to call me if he ever changes his mind. 

Is there anything I can do to ideally get them to not list the house and sell to me, I’m assuming there might not be many options, especially since the sister and I had agreed on a price that was below market value given I was planning to invest money to remodel the home and was planning to honor his wishes of not having the home knocked down to make a townhome or new home.

One of the identical units a few doors down sold for $669k in December and we listed ours for $645k.

As far as analyzing deals, I use a combination of AirDNA, Data Rabbu, and doing my own comp-shopping on VRBO and Airbnb to estimate occupancy and nightly rates. 

You may need to shop this.

I know BP search isn't very effective in pulling up and listing by date, so I'll try a general post.

Are their listings detailed with good-quality photos?

There's a lot more involved then just listing on the MLS, and if you're not comfortable handling the complete process, yourself, you can wind up in hot water and costing you more than if you used an agent. 

I recently purchased a small portfolio in Oklahoma and I found that opportunity because the MLS listing mentioned the other properties, and suggested the owner would be willing to discount them if someone purchased all of the properties together.

Now R3 owners know their properties are going to increase in value, rents are going to climb over the next few leasing seasons, and it might pay off to hold out on listing their student property.