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A simple search and score at your local craft store, a needle, thread and thirty minutes of your time is all you need. (left, Set of three found at Joann Fabric, $2.09)
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Tres Chic Bonus Points: Go green with ebay! (After all, you are recycling!) King of unique and one-of-a kind pieces, and often times, the price is so right. (right, 24 pcs. $.99)
Indeed, buttons and more importantly button holes come in different sizes. Before you fall hard for something that won't work, measure the area or simply compare (or be aware) what you're looking for.
Thirty minutes of your time. Check out this how-to video for those that don't believe me. (Video less than three minutes :)