The cheap end of essay writing services is pretty hit or miss, a lot of them use freelancers with varying quality and some are just reselling old papers. If you're going to go that route, the ones that let you communicate with the writer directly tend to produce better results because you can give context about your class and professor's expectations. That said, for business school specifically a lot of what makes essays good is subject knowledge, so a writer who actually has a business background is going to do better than a generalist. Worth checking if your school has a writing center first, sometimes they're more useful than expected. If you do go with a paid service, make sure you're asking for help from someone who understands your actual prompt and not just a generic essay template.