Ofcourse you can swap csotumes with friends. With a different make up even your closest friends won't notice.
But you can also rely on what you have.
A black dress or black t-shirt and trousers will do great as a basic costume.
A mask, and vintage jewelry will do the trick.
And how about using your bicycle lock chain, if you have one. It's great not complement a men's costume, and it also gives perfect halloween sounds.