Join Date: May 2009
Bikes: Salsa Fargo, One-One Inbred 29er, Blue Norcross
I honestly wouldn't waste my money on an extra wheelset. With weather changing back and forth, eventually you are going to make a bad decision and ride in on unstudded tires, especially once you get a feeling in the spring for how fast they are (plus even changing wheelsets takes time). That is when you will wipe out, and hopefully emerge unscathed but shaken. I speak from personal experience (changing between bikes, not wheelsets, though).
If you do go with a second wheelset and have 26" wheels, you can buy decent disc mountain wheelsets for around $100 (I often use Jenson USA). For 700c disc, I am not aware of as cheap of options, though you could get a 29er wheelset (same bead seat diameter) in the $150 range; I personally start building wheelsets at this price point, since you can get a better wheel for the money. If you go the mountain bike wheelset route, make sure you don't run too narrow a tire on them.
Regardless, try to figure out what sort of snow you will be riding. Does your area plow the roads/paths religiously, so you only need to deal with ice? Will you be riding on lots of packed snow? If packed snow, you don't need as many studs (they are there for ice, which you will surely hit, just maybe not in large quantities), but a wider tire helps you float over snow helps. If you will be riding significant ice, get lots of studs so you don't get knocked over when climbing out of an ice rut. If you are riding lots of snow and ice, well, get a wide, heavily studded tire.
Either way, make sure you are spending your hard-earned money on carbide studs, not steel studs. The former last years (I have 2-3000 miles on mine, and they are going strong), while the latter may last a year.
Last note; get fenders, or get soaked with sandy, salty slush.