I have MBPr 15' model (2012). Go for Retina display model. Believe me it's worth it. Also go for 256GB model. Note that both RAMS and SSDs are not upgradable i.e they are soldered into the motherboard. So If you can afford go for the highest specs.
8GB ram works if you are not doing graphics works but if you are doing graphics work then it's not enough and I would say go for 16GB.

Also I want to warn you that all MBPr (LG) screen suffers from "Ghost Image" effect. There is a command to check whether your display is Samsung or LG. Always go with Samsung display panel. LG has better display but it suffers for Ghost Image.
You won't see it immediately after you buy it but you will ultimately see it. Good luck. There are couple of websites where you can compare your price. Amazon, Ebay, Apple, http://www.macmall.com etc. Compare the price with shipping +tax and go for the best deal.

Only thing I liked about MAC is it's software stability & better trackpad. I have 4 windows laptops and 1 MBPr and I see the difference.