winter tires are pretty expensive unfortunately. the good thing is that they'll last you 5-10 years if you take care of them. so they are worth it in the long run... just hit you hard up front.
the tires will run you 100+ each... with the really good tires costing upwards of 140.
the kicker is the rims. you will need to be rims to go along with the tires, and even the cheapest ones will be 50 each... so right there its gonna cost 200 for the set.
if you're really hard for cash and dont mind buying used, check out kijiji (like raptorman suggested). theres usually good deals on there.