I don't think you need to price anything. Just click on the stall and select 'open for business' and then stand there. Customers will start to come by the stall and you just start to interact with them. There are 4 blacksmith interactions - compliment taste, butter up, hustle, and ask to buy goods. I think you keep interacting with the customer until you are ready to ask them to buy - not sure what increases your chances of successfully selling an item yet, but you might want to check the merchant thread because I suspect it's similar. When someone buys an item you will get a pop up message that tells you what sold and for how much.