I don't know why you can't find parts, as its the same bike as 520 EXC except for the large fuel tank. KTM, Polysport, and Acerbis all sell plastics for this bike. You can swap the 3.7 gal. tank for a SX (2 gal.), or a EXC (2.1 gal.) KTM tank, (03 or newer will be orange). (each are under $ 200), Or if you need more fuel capacity, try either Clark (3.1 gal.) or IMS (around 3 gal.) tanks. (each around $ 200) If you swap to any of these tanks, you will need to also need to get radiator shroud plastics, but you can then up-grade to 03 or 05 style shrouds, both will fit. I use Polysport plastic, (its less expensive than factory KTM plastic), but looks and fits just as good.
This bike is a great all around or dual sport machine. Keep it,ride it, and enjoy it.
Good luck!, KTM Kid 86
03 KTM 250 SX (for sale)
03 KTM 250 EXC w/ 450 cyl. (decked top & bottom) & piston. now 351cc (sons)
03 KTM 450 SX (for sale)
04 KTM 525 EXC w/ Baja Designs kit & Ca. Lic. plate
06 KTM 250 SXF (sons)
06 KTM 450 SX