If you recognize what this costume is based on, you rock.
If you're not sure what you want your pirate costume to look like, my first suggestion, as always, is search images on the internet. Besides looking for "pirate costume" search for "pirate faire." Just looking for "pirate costume" will probably only list the prepackaged ones at the Halloween store. And those costumes are an absolutely fine place to start. Looking at even more images though will help you decide where you want your costume to go. Think about the following:
- Do you want to wear any kind of head covering? Besides getting a hat, you can also get a do-rag type cover as seen here. Unless you are a talented milliner, you're probably going to have to buy a hat. My purple pirate hat in the above picture is from a company called Hattitude. The hat in the second photo is from the local Party City. It was modded with scissors and coat hangers. The hats at the local costume store are a fine and affordable option at around $30. It is easy to remove the garish trim they usually have and replace it with something more lovely from the trim section at the local fabric store. You can rip the old trim out with a seam ripper or small scissors and hot glue the new stuff in place.
- Do you want to wear pants or a skirt? If you're a guy, it's probably going to be pants - but you can choose between tights and something a little more baggy. If you happen to be at a renaissance faire before Halloween, shop there. If not, check out the Halloween store that's probably set up shop in the nearest big city or visit Dress Like a Pirate.com. I've purchased very affordable, comfortable, and decent quality pieces from them. The black skirt in photo one and the tights in photo three are from them, and I wear that black skirt with costumes a LOT. They have great options for men and women.
- Do you want to wear a corset, just a peasant shirt, a tunic, a vest? You can make any of these options work. Check your reference research and see what idea suits you. Check out the site linked above for several different styles of shirts. If you want to get a corset or bodice, Damsel in this Dress is a fantastic source. She also has affordable skirts and peasant blouses.
Shoes can be the tricky part because they usually aren't cheap. Before I happened to receive the boots picture above (I was lucky, someone gave them to me) I just wore a pair of Target brand black knee high boots. Payless might have something similar. The other alternative pre-boots was wearing a skirt that covered my shoes and wearing sandals underneath. If you're going to a party, stiletto boots are probably not a good idea for your feet. You can make suede boots and leather sandals work. Though if you go to renaissance and pirate faires a lot, comfortable and period shoes are a really smart investment (I just got my first pair of sandals this year after attending faires for 13 years. I have no idea why I waited so long).
Daggers, revolvers, swords, parasols, tankards - anything that's going to be carried by a belt or actually held by you. That's what I consider to be a prop. My standard pirate belt includes a leather bag, a mug, and a revolver that is really one of the Halloween store plastic guns repainted. I also have a mini dagger that I clip on. I don't want to be limiting, but the best place to buy most of these things if you want them, is at a renaissance faire or some place similar. They might be overkill for Halloween anyway, but they are nice touches to round out your costume.
Pirates plundered. Though there are probably rules about what kind of things pirates really wore (like at renaissance faires, only royals are supposed to wear purple), unless you really care about authenticity, ignore them. For perfect pirate rings, either hit up a store like Forever 21 or Claire's (there are plenty of flashy things there that will work) or visit the local craft store and head to the button aisle. Picture the buttons on your hand. You can glue them to an adjustable ring base (in the jewelry making section of the craft store) and tada - beautiful rings. Use long strands of plastic pearls or gold-plated chain if you want to wear a necklace.
I'm putting scarves under this section too. Pirates had swaths of fabric wrapped around their waists. I usually wear a purple one because I like the way it looks and then I also have something to hang my bag and mug on. After you have the base layers of your costume done, hit the fabric store for ideas and just buy 1/2 a yard or less. Cut the sash without hemming, dye it or age it if you want, and tada - belt.
Think about make-up last. If you're wearing a grubby pirate costume, don't forget to put some dirt or grease under those fingernails and use make-up (or real dust/dirt - it's easier) to scuff up your face.
Hopefully you can see how you can go very basic with these pieces or you can go full on pirate with thigh high boots, a fancy sword, and luxurious coat. It's what you want and can afford to make of it. In each of my costumes, the price of the corset or vest/coat is really what pushed the cost up. If you leave those out, you can still have a lovely costume that sets you apart from the crowd of landlubbers.