I'm actually now comparing the Bravia 46vl150 to the Bravia 46v5100 (BB deal going on right now)
It seems the only difference is the 70,000:1 on the Costco model vs 50,000:1 on the BB model. Also, the exterior casing is slightly different.
I don't think those two differences justify the Costco model over the BB PS3 deal going on right now...
we'll see I guess.