Im seeing the price of the rMBP at NZD $3,438.01 - http://i42.tinypic.com/2jc8x08.png
I see what you did there, took the base cMBP and comparing it to the high end model for the rMBP. No, take the base of BOTH models (hence the 2.4 GHZ rMBP, and select the 2.7 GHz upgrade)
Yes, but if I pick that one, can I upgrade the RAM later? I'm only interested in options where I can upgrade to 16GB RAM, so at the very least I'd have to select the 16GB RAM option for the 2.7 GHz upgrade (but keeping the SSD at 256GB), or if I wanted the larger storage, the high end model that I previously selected.
However, I understand the point you're making... if you value the display and CPU above other considerations, then the 2.7 GHz 15" retina would seem like a good basis for comparison and at that end of the retina range you're right. The price really isn't on a totally different planet from the cMBP equivalent.
I'm coming from the other end, where I've got a late 2011 model 13" cMBP and one day I'm going to need a replacement. I expect I'm going to need more than 8GB RAM sooner or later, I'm still going to need wired ethernet and perhaps just a modest bump in CPU, on my next machine.
But I'm not sure what that replacement would be other than another cMBP, but fortunately I can upgrade RAM, SSD and wait a few years to see what apple come up with.