Further, the area in which the duplex is located has an extremely low turnaround for tenants and by putting a sign in the yard and posting add on craigslist, most are rented within 5 days with landlord pick of multiple potential tenants.

However, i just want to add one thing.

This average cost plus a 10% add on could be divided equally among the four units.

I would add one more question to Benolyn's list...What guarantee will the PM give for tenants they place?

I know Builidum has some interesting add-ons for maintenance (i.e. online inspection reports, etc) but I've never taken the time or money to truly consider them.    

@Kody Hunter you would only get additional coverage for the LLC if you are planning on doing work for others. 

Value-add on Class B deals.  

You pay a few bucks more per sub but it is a lot better.I would add on to what Jim is saying as he has some good key points.

When you add on the penalties, added interest, late fees and attorney costs - it often quickly exceeds market value.

I'd like to add on a couple of questions to the OP's question.