There is no (not to my knowledge anyways) a off-brand JLF or LS-32 shaft extender.
After Market longer shafts include:
Focus Attack as a extended hollow JLF shaft for $14.95 and
Paradise Arcade Shop has the LONG JLF STAINLESS STEEL HOLLOW JOYSTICK SHAFT (JLF-S9F) for $15.00
It will change the dynamics of the stick by increasing its throw. Longer handle = Longer throw.
double check and make sure nothing is shorting out your O button or K2 button.
All it takes is a single blob of solder or a single strand of wire.