Hi Iveta,
My best guess is that these are wholesale suppliers selling to the public at eBay. :(
eBay has become an extremely competitive marketplace and it is not uncommon to find products selling at prices the same as or lower than wholesaler. Lots of wholesalers sell on eBay directly to the public! Unfair yes, but its the reality.
What can you do about it?
* Order in bulk quantities to drive the wholesale price down
* Sell on another auction site other than eBay – there are heaps to choose from and profit margins are usually better.
* Buy liquidation – this lets you get product for pennies on the dollar. (I’ll let you in on a secret, this is how lots of powersellers make money on eBay these days)
* Find a niche market with few competitors – collectibles and one-off items have amazing profit margins, even on eBay.
Hope this helps. :)