It was cheaper to run (power, heat, space) than the equivalent pile of X86's of that era and for years to come. Each box cost between $250k and $750k depending on cores & memory. You didn't buy one unless you had a specific scaling problem that scale-out x86's weren't cutting it.
What did that board cost you if you don't mind my asking? What does it cost you to run it is maybe a better question.