I have a pair of $10 fleece gloves from Costco that I've used down to 25 deg. F and my hands have been fine (on a 1 hr. 15 min. one way commute). Right now Costco has a fleece lined gloves with an outlast liner that are advertised as weatherproof for $10. I got a pair, but I haven't tried them for commuting. They seem like they'd be just as good as the others I have.

Costco also has a pair of Head ski gloves, with the over-the-cuff gaiters, a handwarmer pocket, and an Outlast liner for $14. I used these on my motorcycle until I got real motorcycle gloves. They were fine on my motorcycle down to about 40 deg F (keep in mind, I was going as fast as 65 mph).

I also have a pair of REI One gloves (currently $34.50; I got them on sale for $20), but they're not as good as the $10 Costco gloves. I can't imagine why one would spend any more than $10 - $15 on gloves for winter riding.