I've been on the other side of this. Big company was under the impression they could ultimately save money by switching from an enterprise ERP solution that costed them hundres of thousands of dollars in licences with an inhouse one. The only problem was the ERP was carrying 90% of the company on it's shoulders and this would've been a horribly large task. I worked on it for 2 years with incompentent managers and slow progress. After I left the company they continued for another 2 and then quit that endevour. Wasting a shitload of money (think 10 devs + managers for 4 years...).