Who are you comparing your prices against on eBay and what are you comparing against?
It's easy to say that eBay has cheaper prices some some suppliers, but that's a pretty broad statement without identifying how you're measuring that. For example, are you comparing a wholesale supplier's price with a, eBay seller who is buying wholesale?
If so, are you using the same volume they are purchasing in to base your supply price against?
Apples against apples, not apples against lemons. If you're comparing a dropship suppliers price against an eBay seller that is buying in large discounted wholesale volume and then selling on a tight margin to create marketshare, then of course a dropship price can't possibly compete against that seller.
So the question has to be asked, who are you comparing your prices against?