Pedal bearings (friction and spinning) My wife recently upgraded her pedals to LOOK carbon and we were very nicely walked through all the different types of pedals from $100-$400. 

I was amazed to see how hard it was to spin the cheap pedals (Is $100 cheap?)

She settled on the $250 version.

My question: Will it really made a difference for pedaling or are the more expensive pedals just lighter and smoother? I am thinking that the $100-150 would have been fine. The friction created by the cheap pedals can't be that much where it actually encumbers your riding?
Negligible difference. More expensive pedals will have higher end bearings which should spin better, but what you're really getting there is a bearing that should last longer. The more you pay for a pedal, the lighter it should be and the longer the bearings should last. That's really it.