The thing is you don't NEED much in aftermarket parts. All that you do need is available. What you won't find at least yet is the bling like orange anodized gas caps and resevoir covers.
One other thing I'll mention, at least from my personal experience, is that KTM customer service absolutely sucks compared to GasGas. My 300 EXC had a cracked subframe from incorrectly pressed in inserts, it was not uncommon. KTM's idea of a solution was to not send another subframe until they got mine back, inspected, and approved warranty on it, leaving me without a bike in the meantime. I said screw you and welded it, sold it, and bought my first GG. This is a big reason why I would never buy a KTM again. By comparison, my '03 GG had a leak in the side cover. The dealer at the time found one in stock at another dealer, and had it shipped to my house overnight. I sent my original back and the warranty issue was delt with secondary to getting my bike on the trail. Thats service.
What other mfg specific forum can you go on where you can directly communicate with the importer?