Beswad, it entirely depends on which category you are listing in, there are different rates for different categories. You pay for eBay listings (unless it's a free weekend) based on the value of your item, then you pay eBay a small percentage of the final sale price.
I have sold things for friends before, I wait until the item is sold then see how much the charges (and the postage) come to, then give my friend the net amount. You can't name a fixed price because if you sell it for more or less, the eBay end charge will be different.