I am going the exact opposite direction, we have two accounts.

. $50k gets you the house but leaves you very little room for value add. 

Unfortunately, you have no power over the tenant until you own the property.

If the landlord's lease with the other tenant provides that tenant the exclusive right to sell certain products or services at that location the landlord might have put themselves in a bad position.

Either way, congrats on the home run of this purchase!

Water from the well has sediments and water forms a yellow lining in toilet.

There are a lot of different avenues in real estate and it can be overwhelming when you first start out, but my advice is to just get the first deal under your belt.

Look for 4+ units seller finance, in the Chicago area 

Do you or most landlords comply with the city ordinance to get their properties inspected & registered by the city?

I imagine there will be others that follow a similar model.