Not that this particular bike is rare, but it's hard to find parts for just about any bike. Most of these bikes were bought for kids, and a lot of kids would wreck the bike and bend up the fenders, clutch covers, and gas tanks. So, being kids, they'd remove the busted parts and they'd end up in the garbage. 40+ years later, most of the good parts have ended up either hidden in a barn or garage on a bike somewhere, or have already found new homes on restored bikes or restoration projects.
That being said, MTD bikes seen to pop up pretty often, but some parts are harder to find than others. What parts are you looking for?