I don't want to speak to which strategy you should use for decreasing your costs, but I would recommend examining your tenant screening process if you are having to actually go through the whole eviction process that many times.  

Properties in good condition that are priced right are going to sell quicklyThe one caveat with a HUD home as there can be a small issue such as a faulty shut off valve that will prevent a buyer from activating the water and prevent an owner occupant from obtaining an FHA,VA,FNMA loan and thereby drastically decreasing the pool of buyers and thereby creating opportunities for investors. 

This is about right as there will be new meters installed, digging the meter pits, new supply lines etc.The question, do I spend the money on decreasing the expenses at the fourplex property or invest in another duplex for about $15k down which will provide about $3600/yr cash flow?

If you decide not to increase rents for several years, you will be losing value on your asset.Remember, if the market begins to decrease, tenants will expect you to lower rents.Gino

Initially my thoughts were to decrease the repair cost estimate I received from the contractor by 10k then recalculate the value.

I guess I am a bit more worried about a bad PM company which could lead to even more of a decrease of return. 

Credit and Liquidity Issues so when the nation's banks face a credit crunch, often caused by a higher prime rate, its profit margins and cash reserves can feel the pressure, resulting in decreased lending in the overall economy, and consumer spending. 

Silicon Valley Job Growth and RE Price Appreciation@Gloria Mirza, I agree with you on job losses and/or recession before price decreases..You can see there seems to be a pretty close correlation to the rate of job growth and the rate of real estate price appreciation in Silicon Valley.

This was fine because as the owner of the house, it was my responsibility, however, it decreased my profit at the end when he did end up buying. 

Is it better to have the highest basis possible to increase depreciation and decrease the amount of taxable gain at sale?