I've said it time and time again! If you have money to invest in your wardrobe, you should most definitely invest in pieces that won't change with a fluctuation in weight like shoes.
There's no better time to invest in designer digs than during the end-of-the-season sales. This is not the time to play around and walk the line! BUY NOW and decide later. Retailers have decent enough return policies where you will have at least 14 days to return once you've received the item. Net-A-Porter gives you 28 days! That's more than enough time to try it on and see how you really feel.
There's nothing worst than seeing something that you should have bought and then having it go "unavailable" online.
Don't let it happen to you!