It all depends on the size, condition and materials used.  

I can probably get $1100-$1200 per month on a new similar sized rental, drop the insurance costs in more than half, and get rid of pool and lawn care.

A small addition costs more per square foot than a large addition.Your best bet would be to find a couple projects in the neighborhood you want to do it in and hunt down the people that did them and see what it cost them and then back into the cost per square foot.

Finding private money will probably be your best bet. 

Check the laws and bet on the opportunity.

Stay on this site read all you can, listen to the podcast, you will find that every one is in different situations and there is not a one size fits all plan, it will be up to you to determine your strengths and weaknesses to determine what niche you have.

The cost of other (non-new construction) houses in the neighborhood have no relationship to the cost you'll incur to build a new house.Your costs will be based on a lot of factors:- Location- Level/type of finishes- Style of house- Size of house- Whether you GC it yourself or hire a builder- The types of contractors you use- Your negotiating ability- How strategic you are with your designs to keep costs downI've built houses for $60/sf, and I've built similar houses in other locations with different contractors for $90/sf. 

That's why I want to consider staying here For the start of my investing.I just didn't know if renting or selling was my best bet.

Rents are $850 for this size unit. 

Depending on the size of the complex assessments can run into the tens of thousands of dollars for each owner!