This photograph is over a year old (John still had hair then!) but I think it's a nice Fall outfit. Alexi Lubormiski shot him for GQ's August 2007 issue.
Jacket ($75) from Yes Style. Yes Style is a Korean shopping site with a lot of fantastic clothes that change practically every week. There's a gray variant of the jacket available.
T-shirt ($9) from Hanes.
Houndstooth pants ($29.90) from Heritage 1981.
Necklace ($12.90) from American Eagle Outfitters. It's not shown in this photograph, but if you check out the complete photo set from men.style.com, you'll see that he's wearing a necklace in the same outfit.
Sunglasses (GBP140 or $257) from Dior Homme. I say splurge. It's a nicely done pair of sunglasses.