On more complex septic systems, you can be in the $100,000+ range or higher depending on how many units the single system serves.In addition to the above, the regulatory environment is a moving scale.  

The complex also backs to the new light rail station that just started running. 

Also, for larger complexes and operations, Yardi and OneSite are good (from what I hear).For smaller to more intermediate operations, Apfolio and Buildium are supposed to be good. 

It was simple at my place I have no idea how complex that might be for you, but just wanted to let you know my experience.  

We paid all cash and bought the complex for $1.2 million.Two years later, after roughly $400k in repairs and operational expenses, and bringing the property to full occupancy, we refinanced the property and pulled about $1.8 million out.Today the apartments are still fully occupied, rents have gone up and it is currently valued at between $5-6 million. 

Small apartment complex.

I have a common area parking and access agreement with the other owner of this medical complex.

I have been bootstrapping the renovations as units come open, which has worked well as I don't have a big reserve fund and I want to keep what I have for a rainy day, (like a sewer pipe reconditioning project that just cost me 12k)With that being said there are other properties in the county that are similar to mine but are a condo complex and units are available to purchase individually on a regular 30yr fixed loan.   

However, for Multi-family complexes it starts to break down for 1 simple reason.

Apartment complexes are the natural progression for RE investors after they have earned respectable cash reserves.$100k is a pretty respectable amount to consider investing in an apartment complex( 12 to 25 units perhaps) which gives you lot more benefits with lesser work, due to economics of scale.But apartment complexes are a totally different ball-game compared to single family and requires a knowledge base considerably different to that of single-family knowledge base.Having said that, I know people with sizable cash reserves who jumped right into apartments without touching SF houses.Based on your post, I cannot advise you to invest in apartment complexes because it seems to me you need to get more experience/knowledge under your belt.