I sincerely hope that there was a specific redemption that drove this purchase end that you got good value out of it.

I suspect the reason that nobody knows the answer to your question is that, even with the 100% bonus, purchasing MileagePlus miles in bulk quantity is something that few people on the board will do. They depreciate in value extremely quickly, and even half-price it can still be difficult to find a redemption that provides substantial value over what you spent to acquire the miles.