Imagine opening a shop, posting some items to sell and buy, but something distracted you... you come back and finish up. Next time you log in you realize you forgot to set one of the item's price! By default you've paid $1 for each item and in a lot of cases that's bad for you (at least on server I play on).

I'm suggesting that the shops default to a null-ish price that disables trading till the shop owner(s) set it. Maybe that item can be set to "Coming soon" in red text like it is when it's sold out.