Your numbers are pulled out of a hat and as a result, any subsequent statistical analysis is meaningless.
I wouldn't say that they are pulled out of a hat. What they are saying is "if you have no dev knowledge, it would take x hours at x cost per hour to build it". The entire article is subjective. If you can code, it's virtually cost-less minus servers..etc. if you can't, cost is based on the dev's charge, the dev's location, is it a single person or a team?...etc. really... A pretty pointless article.