I have to agree that your items are overpriced - don't forget that buyers are paying for the postage as well as the item price.

For example, you have a very obviously used hose connector up for £7.95 plus £2.26 postage, and on your page sponsored sellers are offering a new one for £2.56 with free postage. A new branded Hozelock one is showing as £2.85 free postage, so there is no reason why a buyer may be interested in yours.

I'd take some time to check what other sellers have listed similar items for, and the price they've sold for.