If the splines are stripped on BOTH sides your looking at $600-800 to fix and include the bearing support shown in the link below. If just the female is bad, its about $450.
Also there are three version of the shaft (and now the newer 4th that is completely differnt) The first is terrible, smaller diameter then all the rest, if you have that model to bring it up to par could be another $100 or so.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=turbo&Number=256308&page=&view=&sb=5&o=&fpart=1&vc=1