What is strange about paying for tools that improve productivity? Unless you consider your own time worthless you should always be open to spending more to gain more.
Fortunately, there was enough work to be done so productivity increases didn't decrease my billable hours. Even if it did, I still would have done it. If it helps me help others, then it's good for my reputation. Thats hard to put a price on, but absolutely worth what I paid in this case.