My suggestion would be to interview two or three Realtors and have them evaluate your situation and make proposals.
Go ahead and try it on your own, you might get lucky and be able to sell without professional representation.
However, due to the current economic and market conditions the odds are that to sell you'll need professional representation. If you opt to go with plan B, then you'll have a Realtor in the wings, ready to go.
If you look at the link below, homes are selling. But from the looks of it only about half. So to make sure that your home sells, it will have to appear to offer the most value to buyers, otherwise they'll just buy another property.
Buyers are represented by an agent about 90% of the time, so by selling without professional representation you are probably working with about 10% of the buyers. Does that sound like a strategy to get the highest price?
Also, do you think that the Realtors know market prices and values? My buyers actually are very market savy too, so we do not waste each other's time looking at property that is over priced.
The fact that other properties like yours have been selling while yours did not begs the question - why?
As the Realtors you interview that question and you will learn alot.