Avoid ebay when buying non-firing replica pistols. You can almost always get them for less by shopping around online. This isn't always the case, but replica pistols are often cheaper through a distributor.
Look for sales. Find places that offer clothing and accessories and then be patient. Sales come along all the time.
Make as much of your own costume as possible. Then it is both unique and you can brag about creatiing it yourself.
Try to buy from other pirates. This helps them sell their goods and it keeps everything in the "family". For instance, this month alone I'm buying items from three different pirates here on the Pub. This helps them continue in their craft and it means that my costume is unique, hand made and one of a kind.