In areas like you mentioned you can go on the MLS and still find discounted properties fairly easily. 

You stated you have a contract.. so your bound... if you didn't have a penalty clause like if not completed by XXX date you'd get a discount,  then you get to pester and babysit him till it's done.  

I’m looking to buy my first rental property which coincidentally has been owned by the same folks for twenty or thirty years and is also about $1,200 a year in property taxes.I called the Champaign County Assessor’s office to inquire about a possible change and the clerk who answered said that there were no exemptions in place that would discount the tax amount and that it shouldn’t change.

What's wholesale/discount to a landlord is different from a rehabber.

As far as ongoing management that is a pretty standard fee that you can benchmark and give a slight discount versus the professional property mgmt companies.

Take a look (click on it and it will pop open to a new screen):Maybe FL is just super expensive, or maybe I received the nice guy discount on my closing costs:).

For one thing you could purchase a fixer at a reasonable discount.

Is there software or a resource that classifies neighborhoods?

They get a $25 discount.

You'd be looking for properties that are specifically under-valued, either because Seller's don't have money/knowledge to bring their property up to what it SHOULD be worth, or the Seller is motivated for quick sale so would take a steep discount, or the property has some other unrealized potential such as sub-dividing, or raising rents a lot.