Winter tires are a must for anyone that lives in a cold climate, not just a snowy one. They have been shown to be more effective when the temps drop below 45 then all-seasons. Even the cheapest winter tires would be better then running all-season through the winter.
If you do a lot of highway driving though I would strongly suggest getting performance snow tires, they handle higher speeds better and keep the car more stable by have firmer sidewalls. I went all out with mine and put the Michelin Pilot Alpin PA3's on my car with 17" Momo Winter 2 rims. You can go a much cheaper route you could get Michelin Primacy Alpin PA3's or the Dunlop Winter Sport 3D's. Both come in 215/55R16 size and you could find a set of steelies that will work.
I also recommend Discount Tire Direct as they have free shipping opposed to Tire Rack which requires your first born.