39, EBAY详细答案。

产品包运费99centS，只拿你Link的小铝片做例子，换个产品算法不同。 These are all based on the best scenerio.

如果Seller在中国，从中国运。
Ebay listing fee: 3cents (because seller has over 20,000listing, otherwise more expensive)
Ebay transaction fee: 10%=10cents
paypal transaction fee: 2.1%+30cents=32cents (because seller has over $40,000 sales per month, otherwise more expensive)
Product cost: 10cents (just my guess)
labor cost: $480/30day/500 = 3 cents
               $480/month/worker (RMB3000/month) can handle 500 orders of this product per day (other bigger product may cost more)
               Note: this worker works 30 days a month, 10 hours a day.
Envelop and postage： 25cents (my guess)
warehouse and admistration cost: 1cent
Total cost: 3+10+32+10+3+25+1= 84 cents

Seller net profit = 16 cents/order
monthly net profit = 0.16 * 30,000 = $4800 ， Pretty Good ！！

如果Seller在美国，从美国运。Seller net loss = 24 cents/order
Ebay listing fee: 3cents (because seller has over 20,000listing, otherwise more expensive)
Ebay transaction fee: 10%=10cents
paypal transaction fee: 2.1%+30cents=32cents (because seller has over $40,000 sales per month, otherwise more expensive)
Product cost: 15cents (just my guess)
labor cost: $2000/22day/400 = 23 cents
               $2000/month/worker (including insurance and employment taxes) can handle 400 orders of this product per day (other bigger product may cost more)
               Note: this worker works 22 days a month, 8 hours a day.
Envelop and postage： 35cents (my guess)
warehouse and admistration cost: 5cent (my guess)
Total cost: 3+10+32+15+23+35+5= 123 cents
Seller net loss = 24 cents/order