Used to be that in order to become a legit fashion designer, you had to go to school (or at least appear on Project Runway).

Nowadays, you just have to date someone famous.

Sienna Miller’s turning lemons (Jude Law’s banging the nanny) into lemonade via her brand-new line Twenty8Twelve, a collaboration with her designer sis Savannah. The name hails from Sienna’s birthday (she’s an actress — of course it’s all about her), but the clothing is to die (and not in a Kate Moss for Topshop disappointing way).

Channel Edie Sedgwick in the brown leather biker jacket with sleek, detachable insert. Lure in Casanova in the demure, long-sleeve, gray silk dress with ruffles, pleats, and a waist tie. Be interview ready in black, pinstripe, wide-leg trousers. Do the hippie hippie shake in a pair of distressed, relaxed-fit jeans. And play Alfie’s dating games in the flirty, gray silk minidress.

The pieces are going to cost you.

Guess we all have to pay a price.

Available online at my-wardrobe.com.