Bellatrix Lestrange prisoner of azkaban costume?

Okay, for this halloween i am throwing a big Harry Potter party this year. And i have decided to be Bellatrix Lestrange and at first i was going to try and get/make her death eater costume but i thought it would be a bit difficult/ expensive so i want to make or get the costume she wears when she is in azkaban when she is a prisoner, its kind of like a nighty type dress, a dirty black and white striped dress thing. I live in Scotland so i would need shops relevant to me. Please it would be alot of help, thank you! if you search bellatrix lestrange azkaban prison a picture will come up, thank you!