Ask Lily: Best places to get affordable formal wear for a black tie event

Hello I recently came across your page and blog and I have found them very informative with insights on hundreds of topics. I would like to ask a question on fashion. I have a formal black tie event to attend in a couple of weeks time and I’m on a budget. I am a pear shape with big hips and I’m not too comfortable wearing figure hugging clothes.Kindly advise me on where to shop around and what is best for my figure. Thank you. Alice Photo credit: knox_x