$589,000 is an odd price point by the way. $575,000 to $599,900 is one slice of a pie. How did you come up with that price? If you are offering a 5% co-op, you must realize that a buyer is simply going to knock off 5% to 10% anyway OFF almost any price (no matter how reasonable and aggressive it may sound) *That's why they are shopping "By Owner."
Consider interviewing a few different agents. Look at the big picture. Is a matter of what you pay or what you NET here? I think you realize that you have money to work with in teh transaction. Now what you do with it is entirely up to you.
Personally we are not seeing much sell right now by owner. With the relative lack of buyers, it is hard for a by owner to reach them. The buyers are working with agents and the agents are looking in the MLS for homes to sell. It is not impossible, but the odds are probably stacked against you. Of course, I hope it works out for you this way, and I understand you have tried listing in t he past.
When builders are in a market, still trying to sell new homes at a price less than the homes they sold a few years ago, this pushes prices down. That is quite common right now.