I think the responses have all been the same, and I'm only going to add to the PI parade.

I got the AmFIB tights last year on close-out at the local REI. I have LOVED them. I ride daily through Minneapolis winters, I wear the AmFIB tights, with liner shorts, SmartWool knee-high socks, and Chrome knickers down to 0F (after that I add a wind-blocking layer over the top). Worth every penny. When I need new ones, I will not shy away from paying full price.