Are you using apples parts in the regular MBP? Because if so, you are doing it wrong. With the regular MBP you can use third party HD's and Ram.
I used rough estimate third party part prices on the RAM and SSD for the regular MBP.
Which is the point of what I am saying, "Apple-tax" MBRetina is cheaper than classic MBP souped up with third party SSD and RAM to be similar to the MBRetina. I need 16GB RAM and planned on getting an SSD anyway. For a cheaper price I get DAT SCREEN as well with the MBRetina, though I do lose out on being able to do a dual SSD/HDD setup by replacing the ODD.