It took a bunch of teams of senior devs and other people 1 year to translate some simple excel sheet with formulas into a little Java powered site on top of a database. The cost was a few $100k and the end result was something most people here on HN can do in an afternoon (max a few days), but tech was never the issue; it was the process & politics between the IT dep (which was in another country (Germany), the head office, the hired consultants (I was one of them) etc. My job was to steer the tech people at a high level (they had their own project manager etc; that was not my job) and the consultants (from another company) that did the implementation kept disagreeing with my approach and everyone else kept disagreeing with everything else (like the color of a button). In the end it was implemented like I wanted it in the first place (and they took the credit) and I heard, much later, from one of the seniors that their PM told them to disagree with me to pump up the final bill. Which worked; luckily I never worked 'with' them again after.