They're damn near impossible to get plastics for - if they're genuine plastics on that one, then that's the starting bid right there... Nothing else seemed to be a drama to get for my 91 WR125, and the 91 250 motor is the same basic design as the one they only stopped making when KTM took them over, so I assume there's no big hassle with parts availability there.
As a bike, they're good. Husky made big steps each year from 90 to 93 - this was the era when Cagiva was moving the bikes away from the old European-only ideas and toward Japanese/American ideas. Being a 91, it sort of sits in the middle with the newer look and geometry, but without the Japanese carb/ignition/suspension/brakes that made the 93/94 models so good.