And also I am trying to be conservative in my numbers, try to keep 20% margin for any emergency.

Unless your margin for cash flow is that tight them you have another set of problems.

Or would their profit margin and construction costs seem to make that unlikely?

Anthony Dadlani I totally agree Sir, but I guess what I'm wondering is when my Realtor sends me multiple listings for investor properties, can I use, say, an avg repair number or rule of thumb to quickly weed out the higher profit homes from the slim profit margin homes right away.

If it's a marginal deal, it probably won't work.

We have done very well by maintaining our already small margins through self management and low vacancy through great home purchases.Another great place is to look around the blogs, forums and listen to the podcasts.

It was hard enough to get the margin we wanted with just the family.

My minimum margin is 5K.

In that case you end up putting a property under agreement that is a bad deal or marginal at best.That is where the new investors get into trouble. 

We have lower margins, less profit but also less expenses.