I'm far from an expert but it was my understanding that although edge retention is comparable, D2 does not possess much corrosion resistance. I would hazard a guess that 154CM would cost more than D2 in equal weight.
Like I said earlier, D2 is generally considered to have better edge retention than 154CM. As for corrosion resistance, D2 is on the boarder line between stainless and non-stainless, so it is decently stain resistant. I live in Hawaii, with the beach down the street from my house, and I haven't had any issues with corrosion (of course none of the knives are actually being taken to the beach or getting wet by the salt water).
As for the cost, well Benchmades with D2 usually cost more than 154CM from what I can see.