I don't know about for the rest of the world, but since generally they sell the same stuff everywhere, I thought I'd pass on that the GAP stores in NYC are having a huge sale right now. Included in this sale are drawstring wenchy/piratey shirts. Long sleeve are $20, short sleeve are $10. The short sleeve is about the cheapest I've seen shirts like that for new, and they have them in white, brown, kelly green, magenta, pink, and yellow. The long sleeves look like they come in royal purple and brown. They're cute and don't have any obviously modern bits (plastic or anything like that, although they're machine embroidered and do have very bright dyes). GAP is also selling really niceleather belts in a variety of styles for $10 (marked down from like $50) with lots of rivets and hooks and things. Good pirate gear for anybody who needs.
ETA: H&M also has a ton of pirate-style stuff on clearance. Not quite as cheap as GAP, but they have better fabrics & patterns, and some cheap corsety things.