the 930 is not far superior...
Better chipset, thrid channel of memory, greater memory bandwidth via QPI instead of DMI and support for full dual x16 PCIe 2.0.
I would say thats superior.
As for the OP, not sure as to the pricing. Intel does what they do. The difference though is a X58 mobo and 6GB of DDR3 vs a P55 mobo and 4GB of DDR3 plus the cost of the former is a bit higher.