I guess it would depend greatly on the item you are selling. Like for auction style format, the insertion fee may be as low as .10 cents or as high as $2 depending on your listings starting value whereas for fixed price format for an item $.99 and up sellers are charged a fixed insertion fee of $.50
You might want to view the table for final value fees for both auction style and fixed price format - Link hidden: Login to view
to get a better picture.
Hope this helps :)