things to consider in order for this to be necessary
do you run in the rain?
do you run in water?
will the water penetrate the shoes from the top (sock line) or will you wear a gaitor as well?
i would only purchase waterproof shoes if i were going to be running in very dense wet--puddles, heavy rain, snow, etc.--otherwise, just buy some proofing spray and spray it on the shoe, which IS what i do now. i run in the rain often, and even through the puddles, without being bothered by the wet. i originally buy the spray for my soccer cleats: we have a rainy season during soccer.