Tons of sites to buy from. Some are better than others. No one site has all the available options. The KTM PP's are great, but some other companies are putting out items that are as good or better IMHO.
Twisted Throttle is good. Bought my sw-motech stuff from them.
MotivationUSA is fantastic. Bought a couple pieces of evotech stuff from them.
Rottweiler Performance has issues with stocking and shipping. They are a really small operation and are getting slammed at the moment. I ordered an exhaust side pillion peg delete from them without knowing it was backordered and they let it sit and wouldn't answer phone calls or emails for two weeks until I finally got through and was able to cancel the order.
Evotech Performance - bought a few pieces direct from them. Shipping wasn't cheap, but it was quick.
Interesting take on indicators/tidy:
KTM 790 Duke Front LED Turn Signals