The saying goes "never say never", but I'm saying it here. Never buy something that is not your size just because it's on sale. You will always regret doing this because it won't fit you properly, and as we all know by now, a good fit is key to looking your best.
The one exception is shoes. You can usually give or take a half size, and maybe even a full size if you REALLY want them, just make you are not limping home.
Yours in style, Style Blogger.