There is some mixed advice in this post. Some good, some ok and some bad.
The first thing to know about St. Louis is that there are actually two St. Louis'-St. Louis City and St. Louis County. Because of laws from a century ago, they are separate. There are actually 90+ different municipalities within those two as well. There is a North City and a South City. There is also a North County, South County and a West County. Each is very different from the others. Municipalities within those areas can be very different from others as well. Even neighboring ones. That contributes to the block by block nature of the region. It looks like there was some confusion about this above.
If I were to boil everything down to just one piece of advice for investing in St. Louis for those not living in the area, it would be this:
I am primarily an buy and hold investor. I invest for cashflow and target rent to purchase rate of 1.2 and above in Kansas city.
I was made to undertand that STL has more affordable houses (cheaper than KC Mo) but with identical rents. However, I do not have any multies and that informed my questions.
So I can take a little bit of more risk with C+ to make more cashflow. The Bs I see in STL are moderatley priced but i am asking more questions while doing more research.
I just signed up with an agent while navigating the terrain.
How much would a good fourplex cost in above mentioned zip codes. Assuming all units are 2 bedrooms, each unit rents between $500 and $600 and each unit is 700 sqft or larger in size. Owner pays for lawn care and trash only.
The numbers can run the gambit in a zip code. There are 4 plexes on the west side of 63118 which are a bad deal at $100k, but others might be a great deal at $150k if they are on the East side of Jefferson. I passed on a 5 unit commercial deal at $60k with $3k in monthly rent in 63116 but purchased my 4plex in 63116 for $120k with $2k in monthly rent and would do it again in a heartbeat. 63109 is one of the pricier areas, but I'm not sure how it compares to the nice part of Benton Park (63118). South City St. Louis is block by block.
However, I'm not an expert on the St. Louis market. I would defer to experts like @Peter MacKercher and @Bob Hines who know the local markets much better then myself.
I would also recommend coming up with a list of questions and a list of Property Managers for each area. Go over the exact same list of questions with each PM. You'll be surprised at what you can find out. The differing opinions are an absolute wealth of knowledge.