If you are talking about your ebay store, I think your sales are low on it because of your layout. The current layout is very confusing and the pricing on it is not very clear. You have to make your store so simple that even an idiot would understand, right now those idiots are confused by the layout. This creates a barrier for them to get your product and makes them look at other options.
Finally, because your price is so much lower than the DigiQ, most people will think its to good to be true. In their mind there has to be something wrong with it, how can you offer your unit at such a low price and still retain quality? I think time and satisfied customers will be the only thing to help you overcome this obstacle.