Take the item the the post office and ask them to weight it and they will tell you how much shipping is... should be no more then $3-$4 I ship games cross country all the time and that the normal price....
see the thing is you have it as free shipping in the us so if someone wins this that lives in the us you have to ship it and they dont have to pay if your new to this be careful when making an auction always place exact for shipping no matter what and if you say you will ship it free if bids are say for ex 4000 you should put that