Depending on the Apple Store online's affiliation with a country or region, the inventory
could change almost daily and can vary from between countries as to frequency of stock
availability. I see there are two models of MacBook Pro 13-inch retina with 16GB memory
today, Apple Store special deals refurbished section online. Both 3.1GHz i7 dual-core 2015.
http://www.apple.com/shop/browse/home/specialdeals/mac/macbook_pro/13
There's also a few MacBook Pro 15-inch retina models with 16GB memory + i7 quad-core:
http://www.apple.com/shop/browse/home/specialdeals/mac/macbook_pro/15
Subject to change so be ready to pounce when your choice of product presents itself there.
Or be on the lookout for other authorized Apple resellers, but note their return policies are
different than those of official Apple Stores. Independent resellers have their own rules.
So the opportunity is a matter of timing, & your flexibility in choice, plus product specs vs cost.
Not usually an inquiry of an App Store thread, since these aren't available through there...
Good luck in this matter! 🙂