It would cost $175k to clone Instagram
pricetaghq.com
pricetaghq.com
The founders described it as "replacing all the components of a car while driving it at 100mph", and even having worked on projects orders of magnitude smaller (albeit with a considerably more complex datamodel) I can't say I disagree.
It's like someone proving out that E=MC^2 AFTER Einstein already figured out the problem.
It's still a cool exercise to do! I wish he would do that for more sites and apps! I bet the Draw Something app isn't that expensive to reproduce.