Lots of people don't have money to purchase equipment, especially equipment that is very specialized. Try Ebay, Audiogon or Craigslist if you are really in a hurry to sell it. Most people today want at least 25% off the new price and some want as much as 60% off.
We had some really good microphones up on Ebay and we had them for about 40% the normal selling price or $250 and a couple of people offered us $25.00. Many buyers today think they are dealing with someone who a)doesn't know the value of what they are selling or b)are in a big hurry to raise money and really don't care about making a lot of money on each sale or c)are selling stolen gear.
What you have is valuable and how you present your merchandise has a lot to do with how quickly and how much you will get for it.
Reason? Like others have said, it's a niche piece designed to solve a problem. if people don't have the problem (ground issues) they don't need it. Guys in the know, know there's easier, cheaper and better ways to get balanced power. Guys who don't know.....well, they don't know. Put yourself in Equitech's shoes. Hang in there, it will sell if you wait long enough.