but they want 8 bucks to ship.
The widget costs N dollars. Some eBay sellers charge actual cost of the item, and actual shipping. Others subsidize the price of the item with the shipping charge. Most people don't check the total delivered cost, and just grab the one with the lowest quoted price. Years ago some sellers were almost giving away MP3 players, but then charged $25 or more for shipping. eBay rule changes stopped most of that, and shipping charges are more reasonable today.
How much do you think it costs to ship something anyway? Priority Mail starts at 5 bucks. Add the cost of packing materials (PM boxes are free but bubble wrap and packing peanuts are not). And then add the time for packaging, printing packing slips, shipping labels, etc. Eight bucks is probably pretty close to the actual cost of shipping one unit.
I know places like Amazon offer free shipping. They negotiated a much better rate from the carrier than the average Joe can get. The same goes for shipping supplies. And I'm sure their shipping department is tuned for maximum efficiency to minimize the costs.
Jeff