Selling stuff and making $$ on eBay - but shipping costs are killing me

Post some examples of the size of the box and the weight.

build the cost of shipping into the cost of the item.

USPS flat rate boxes. I shipped a 40 lb chunk of metal cross country for like $16

Make the buyer pay for shipping costs. I charge $8-12 depending on the item.

Use the shipping calculator eBay provides. Weigh your item then add 1-2 lbs of packing material weight depending on the size if the item. Your buyer is then charged a shipping cost based on their zip in respect to yours. Understand if it is a particularly large item (talking like on the order of 24x24x24 plus) there may be a substantial up charge by the USPS for a large package.

I have no problem selling items with calculated shipping. It may sell for less but if you live on the east coast like me and someone from CA buys a 2-3 pound item then that's almost $15-20 for USPS priority mail and not much less for parcel post. I usually offer discounted or free shipping for media mail or first class (1-13 oz packages) or for items that I know will sell for a few hundred dollars. But it's just not worth it to me to sell a $50 item with free shipping to give back $20 to the usps.

I guess it's just how you choose to do it. I'm a power seller as well but I guess I do sell more niche items and not huge inventory items where you have so much competition.