"it’s pretty painful to list them and mail them one by one at the post office"
- nah, I print the shipping labels though the eBay system and just give them to my mailman.
"So selling one at a time and dealing with shipping is hassle free and worth it?"
- yes, I think so, I buy the cardboard mailers from sellers on eBay, 50 at a time, under $1.00 each. I add the cost of the shipping, ebay's cut and the shipping cost to the "Buy it Now" price.