However, it is important to remember that the housing market can fluctuate.

Remember, you are occupying one of the units...it would be impossible to cashflow in that scenario.

A unit that rents for that much should be worth about $150k, right?

Remember that each investor is unique, and tailoring to their personal needs is the key to real estate investing success

It will be well worth it. 

My question is if this will be worth the money as I will need to dig into the concrete slab foundation and tie into the existing sewage line. 

It's worth about 65k.

One of the things to consider if you manage through your LLC also is if you are doing it for asset protection - just remember if a tenant sues they are suing because the Property manager did something wrong - in this instance they would sue the LLC and the person who was managing it (which is you).

Unfortunately I can't remember the source of that information.  

As where a traditional investment home can be worth a lot more money which requires a higher down payment etc.