If we were to meet i would ask why you are in this situation. I would not give advice with out knowing the reason. Different situations could have different answers.
Here is the deal.
The investor represents himself not you. This presents a conflict of interest. You will likely get 60--70%, if you know the value, if you do not you may get less.
You talk as if a Realtor is to be avoided, when actually they will work in your best interests to get you the best deal.
You also know with a Realtor that they are motivated to get you as much money as possible.
What our team knows is that if we place a well priced home on the market it will sell quickly, probably for 90% of value. Take off the Realtors cut and you still look to be better off.
So the question is would you want 70% or 85%?
Just get a good Realtor-preferably a team- not all are equal. and if you are underwater with the loan read our short sale info on the link below.
The advantage is you are off the property quickly and do not have to do any updating or worry about showing the property.
Unwavering Commitment to Service
An alternative might be to list w/ a Realtor at 15% less than fair market value. If the property is aggressively marketed and you receive multiple offers, the market could push the selling price up. In order to get the maximum market exposure, list the property with a Realtor in order to tap in that segment of the market.
Ultimately, the right decision will be different for different people.