Anytime I've ordered anything in from my LBS that they normally don't stock, I owe them shipping up front. If I decline the item when it arrives, then they keep the shipping. I've never found that unreasonable, because if I order something online and decide to exchange it...well...I end up paying shipping.
Depending on the nature of the item and if they decide to keep it and sell it, they may order a different one in a different size and not charge me shipping the second time around. It all depends on the circumstances.
Edit: Obviously, if it's an item they normally stock, they simply order it...if I don't buy it it goes on the shelf.
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Good night...and good luck