How much is good will worth?

It's spelled as one word in the world of finance and in one case is worth $3.7 billion. That case is Blackstone Group, where a $4.5 billion valuation was placed on its IPO. Goodwill was 84% of the total value.

It appears as though a new legal entity was formed as part of the IPO. That entity, since it bought a company including its goodwill, can deduct the value of that goodwill from its tax bill over the next fifteen years. It's legal and in many cases a realistic way to recognize the value of some businesses. In this case it looks as though they are simply taking advantage of the law and, since the Blackstone founders retain 85% of the new company, the new investors. Basically, they found a way to make a tax-free killing.