upper 40s.. base layer + insulation + shell
I like those thin silk or merino base layers, a thicker long sleeve jersey (or even a merino sweater or some sort of fleece), and a shell
I recently purchased REI's Novara stowable and a Canari shell. Each were under $40. From my research, you want something that doesn't flap in the wind. I sized down on these. The Canari shell has removable sleeves.