Let's say someone who earns $50,000 a year uses Office for 5 hours a day while making a living. It's also a purchased copy so it lasts at least 6 years. What's that worth?
How does it compare with the cost of, say, one Starbucks a day?
If you employ somebody on that salary for 6 years (so add extra employment costs including taxes, insurance, office space and perks), what percentage do you save by not paying Office's shitty price?
Sure, but it's not a replacement for Word, Excel, PowerPoint, Outlook or any of the other Office programs.
The real question is, if vim cost $100, would you pay or would you use a product you didn't like as much, that wasn't as efficient, or as productive? How much would you pay for a Supervim that earned you an extra $5k/yr?