You may enjoy reading a discussion on this very subject here by ultralight backpacking enthisiast Michael Connick: http://www.monmouth.com/~mconnick/clothes.htm

For myself, I choose less-expensive but still completely effective versions of waterproof/breathable shells, such as the Red Ledge Thunderlight series. The jacket can be had for $49 US and the pants for $39 US. I've braved many an onslaught with these.