There is a range of factors you need to acount for when setting the price of items. In my case ebay and paypal combined take close enough to 18 % of my total gross income (total sales price ). I add the FVF on postage to my postage cost and also add a bit extra to postage to cover items lost in the mail etc. On top of this you need to think about holding costs if the item will sit as a BIN for awhile. If you have substantial stock holdings you need to cover interest on the money invested, stock loss or devaluation for slow selling items that eventually need to be discounted to move and factor in that some items may never sell etc. You then need to decide how much profit you need to cover your time spent listing, packing etc.

        There are plenty of ebayers who are probably working for a few dollars an hour if they have not done their maths properly. Personally I need to sell items with a mark up of 200 -300% to make the job pay. You may be able to accept lower profit margins if you are selling higher value items.

example- If you sell an item that costs you $50 for $100 ( 100% mark up ) you will pay around $20 in costs leaving $30 profit  ( or 60% )

                If you buy an item for $5 and sell for $15  ( 200% mark up ) you will pay around $3 in fees for a profit of $7 ( 140 % profit )  but  it will probably take just as long to list, pack, answer questions etc. as the higher value item. You need to sell around 4.5 cheaper $15 items to make the same profit as one $100 item. Clearly you can accept lower profit margins and still make more money per hour, selling higher value items.