BMW OEM Winter Packages are grossly over-priced imo...I've had very good luck with Tire-Rack wheels and a good set of winter tires..I've gone that route on 5 & 3 series as well as X5 and X6 too.
Buyer beware and do your homework on type of winter tire (ie snow/ice vs performance tire, right loads etc..) for example Blizzak has a WS series and LM series - they're both winter tires, but the WS is like driving on rubber bands and I'd never want to own a pair of them again.
I'm a big proponent of winter tires in the snow-belt, but I'm tempted to try my all seasons this year after the mild winter last year
I started a thread on winter tires about a week ago..It's on page 2 and has a lot of good info on it too.
Current Ride: 2013\28xi\Deep Sea Blue\Oyster Nevada Leather\Fineline Sienna Trim\Sport Activity \Cold Weather\Premium\Comfort Access\Navigation\Panoramic Moon Roof\BMW Assist
Previous Rides: E92 M3, E70 X5 35d, E71 X6 50i, E71 X6 35i, E46 M3 Cabriolet, E39 540i, E36 328i