Though it depends on where you live, up here the question is skinny studded or fat studded. Ice is a given, so the main variable is how much snow you're riding through.

I agree that for $30, that is super-cheap winter insurance. I spent a fair bit more than that to get a pair of Marathon Winters (skinny - 35mm) AND a pair of Nokian Extreme 294's (fat - 2.1). Maybe overkill, but as I plan to ride every day, it's worth it to me to make sure I have the right tool for the job.

You can still ride studded when there isn't any ice with no ill effects to the tire (assuming carbide studs), and only an incremental rolling resistance penalty. Unless you have an extremely long commute, I'd just consider this a fitness bonus.