I got by just fine for my first winter of commuting by just buying studded tires. I already had fenders on the bike and it was fully commute-rigged otherwise. Then, all I had to deal with was clothing. Took me the whole season to get that sorted out.
Anyway, I did it that way just in case it turned out that winter commuting wasn't for me. I wouldn't have a lot of money tied up in something that didn't work out. I figured the Nokian W106s would be easy to Craigslist too.
I went hog wild on a new bike for the second winter. It'll be the third winter on this bike, fourth on the snow tires.
Just keep a spare chain and some brake pads in stock, get the studs, and go for it. It it works out, get the new bike for next year.