No problem, it's your call as a seller. It's just that as an unknown person on Listia, very few would be willing to risk paying money for shipping. Too many scam artists that never ship the item. One strategy, if someone is serious about Listia, is to list the first few things without a shipping charge, get the positive feedback and then you can charge shipping. Are you that broke that you can't afford $2 or $3?
To me the appeal of using listia is that it's more like trading items than buying and selling them. So why would I spend money to give somebody something. If they are unwilling to dish out the $2 or $3 for a practically brand new $40 item that's their loss not mine. Are you too broke that you can't afford the $2 or $3 to make sure the item you bid on makes it to you?