Suggest you call a reliable, busy maintenance company like Heli Air and get the latest prices - parts subject to dollar flucs.
Do suggest also that you inform maintenance company how much of an overspeed that you or someone you know has had.
They will have an interesting list of costs of repair which may resemble a graph , like Y=Xcubed or maybe Y=Xto the power 4.
I bet you whatever it is it will be cheaper than someones' life if you or someone else misrepresents the true data.