I would be planning to do some things before actually making an investment.

As we have an accounting firm, note I am a bit biased, but here is what I see folks have the most success do: You should start with an accountant who is very familiar with your investment strategy and grow with them until you cant anymore.

And where can I buy it? 

I grew up in the Western US, where homes are generally constructed the same (broadly speaking). 

Update: I decided I will pay a $500-750 or so to do an initial hydro-jetting of the system. 

I think that matters the most.

With your budget, depending on where you are working, I'd consider Silver Spring or Hyattsville  

What I'm really looking for is a simple platform where my tenant can pay rent online rather than send in a physical check every month (their current system...).

I highly recommend going to meetups and talking to investors in person. 

@Alec Jacobs I have basic low/no fee business checking accounts.