If you have a 2000 up bike, you can get these from KTM:
KTM Hard Parts - Hardened Wheel Spacers
These Wheel Spacers are made of a hardened material that will not wear. This helps maintain a better seal and reduces bearing wear.
951.048 26mm Front (2003-up front)
951.049 SX/EXC/MXC Rear (2000-up rear with non-cush hub)