Good idea! Not exactly a secret specific to Louisville, but anyway... while I'm not familiar with the entire county (which is the city), I've watched the neighborhoods inside I264 and just west of that for 15 years. We're still a small enough city that you can easily discern the path-of-progress (POP) when a neighborhood is getting "squeezed" by adjacent areas that are growing/renovating quickly. Buying at the right time in the POPs, when the neighborhoods are still rough, will give you outsized appreciation. E.g. Most newbies wouldn't consider Germantown years ago, and then everyone wanted a piece of it. That POP moved north into Shelby Park and then north again into Smoketown where houses that were recently 100K now sell for $200K+ and that story isn't done yet. (Who bought that two story on North Clay Street for 140K a few months ago and has it listed for 277K today? I wanted that property! Haha) You can see the culmination of this with the recently announced redevelopment on East Broadway around Shelby Street, which is also getting a lot of positive pressure from Paristowne just to the east of it.
I've posted my feelings about this plenty of times on BP but inside 264 I feel pretty strongly that the next POPs are the Warehouse District (east Portland) and the eastern half of the Russell neighborhood (east of 22nd street). Tough neighborhoods still, but plenty of fixer uppers and low cost plots make it ideal for scrappy individual investors looking to get started on the cheap. I placed a few bets in those over the past few years, so we'll see.
Buying in up and coming neighborhoods, at least around here, is not a get-rich-quick scheme. Make sure your rents support the property while you wait and that you have a view that is further out than 36 months.
Another thought - When purchasing HVACs, roofs, tree removal, siding, etc. you can very easily pay "retail" (just look for the biggest ad campaigns online) or you can save 30-50% by being your own GC and finding or going to the crews directly. Most people are not willing to do this but if you're scrappy you can pay wildly different prices for the exact same thing.
PS. We'd like to thank "Bourbon", if you're here tonight, for all the great things you've done for our city. :)