You have to hand it to the girls at London Fashion Week: they really suffered for their art. It was a heat wave, and yet there were trends that had to be worn: fur, and leather, and specifically, black leather leggings (or, 'wet look' leggings: to me they look like scuba or snorkeling gear). Some were faux, some, no doubt, were the real deal. Two different looks: which would you lean towards?
It baffles me beyond belief to see the cost range for this one simple trend. The Saks Fifth Avenue site lists a range that includes Fendi for $1,850.00 USD (or, for a hundred bucks more, you can opt for the Maison Martin Margiela version, altho I can't see the difference from the shots).
Alice + Olivia has a pair, a bargain at $698.00, but if you don't mind faux, go for the Romeo & Juliet Couture pair which will set up back a mere $35.00. And leave it to Topshop, they've got 'wetlook' black leggings for £18, or $28.60 on today's exchange rate. (I'm not assuming everyone reading this is a Yank or a Brit, so use the XE conversion to figure it out in your currency).
Unless you're absolutely sure this trend will become a classic, I know which one I'd pick.
(By the way: I didn't ask either girl where they got theirs, but the top girl's bag is Valentino. Still, that doesn't mean she hasn't gone for the faux).