$14 – $19 from your local Fred Meyer Grocery Store. 2mm neoprene fishing gloves will keep your hands dry and warm for commutes less than an hour. They can take good downpours but are not seam taped so in heavy downpours water will get in after a short while. The manufacturer Glacier Glove has a whole line up of neoprene based gloves which are not specifically designed for cycling but could be good.
For cycling specific designs and fancier longer ride time gloves with similar materials and qualities, check out Castelli or ShowersPass
Nice idea 😉