The best method to develop a business case is to complete it internally, using a globally recognised, robust business case development method such as Better Business Cases (BBC). Besides, you know your business operations, markets, customers, and finances the best. An external consulting firm or consultant will never know as much you about your business. That is why we recommend getting yourself or your employees trained in using the APMG International Better Business Cases 5-case model framework which is based on the UK government’s best practice approach to developing spending proposals & enabling effective business decisions. . The benefits far outweigh the costs. For more info visit here: https://ezyskills.mystrikingly.com/blog/business-case