With regard to the 'return at your own cost' - there is a very good reason for this.

I run an importing company and distribute to retailers.

If an item is claimed to be faulty then they return to us AT THEIR COST and if it is found to be a manufacturers fault then we replace and return and refund the cost of said postage to the retailer - they are in no way out of pocket.

If, however, we find it is damaged due to misuse, lack of care etc, then the item will be returned at the buyers cost or disposed of at the buyers discretion - no refund or reimbursement of postage.

How is this unfair? Why should the seller be out of pocket if the buyer mistreated an item.

This is not the way it works on eBay I know, however most decent sellers will offer to do this. I simply wanted to point out to the OP that the sweeping statement you made

"Oh the item is faulty - send it back and we will send you a replacement, but you have to pay return postage" - guess what?  Fair Trading say this is BS.  But it happens THOUSANDS of times a day.

Is not so black and white in the real world and there are guidelines for any manufacturer and warranty provider in place, and they are there to protect both buyer and seller.