First of all you are talking about Instagram and I am talking about facebook. If some random students made Instagram who were otherwise making minimum wage it's not like you can claim Facebook should be able to make it for <$1000. Also, it isn't just the app that we are talking about but the server and all associated infrastructure.
But secondly, I'm not sure how you went from 13 people to 3, lets assume we we accept that we are only talking about the 3 people. Even if those 3 people are making only $50k yearly salary, working on this for 6 months is already costing Instagram well over $100k once you take into account office space, benefits and hardware.
But secondly, I'm not sure how you went from 13 people to 3, lets assume we we accept that we are only talking about the 3 people. Even if those 3 people are making only $50k yearly salary, working on this for 6 months is already costing Instagram well over $100k once you take into account office space, benefits and hardware.