You are MUCH better off buying a new shaft. Realize that, in addition to voiding any warranty, it is going to play like a completely different shaft(I know that's what you're going for but..) and most likely NOT like any 11.75 that you have tried.
Your question was about cost. We don't quote prices openly on the forum; bad policy.
You can expect the cost at an 'event' to be somewhat steeper than having the work done locally.
I'm not going to tell you not to do it. I'm not going to tell you it can't be done.
If the wood is aged sufficiently and stable you should be good to go.
Others have offered opinions; you now have mine.