Hi ebay charge normally a 10% on total sales including postage,

so if i sell a item for $14.00 free postage ebay fees are 1.40

if i sell item for $10.00 + $4.00 postage ebay fees are $1.00 then when the buyer pays you get charged 0.40 cents when they complete chechout.

If you use extra fetures such as subtitle you get charged for these features.

if you go to your account you can see what you have to pay.

If you use ebay postage these appear on your account a Day latter, and if any postage discount  10% for the 500g rebate $7.20 ebay postage you normmally recive these  after the your fees are paid.

Total fees ebay paypal fees are around 15-16% of what you receive,

a good tool to work out profit. is at 

http://ecal.altervista.org/en/fee_calculator/ebay.com.au/

hope this helps Anthony