AGS, I think you should perhaps keep your focus to smaller, lighter, cheaper items to ship. The problem you have is even though you may well be able to get a product listed cheaper than the same can be found by shopping traditional retail, a smart shopper will always calculate the shipping cost of having it delivered as part of their total cost of the unit.
The bigger, and heavier an item is, the more the shipping cost and the less competitive you are against offline retail.
Always important to remember that not only are we competing against other online sellers, but there is a more traditional retail world of commerce we also have to be one step ahead of to ensure we are providing products that are hard for any customer to turn down for any reason.
Good that's you're up and away and making some headway, getting the ball rolling is often the hardest part : )