Parts: Yes and No
Phillip:
That KDS-21, imtroduced in '84, is old enough that not every part will be found on the shelf of your local appliance parts dealer.
However, between eBay and the resources of this group, it is almost always possible to find what is needed.
I own a 15-Series KitchenAid Superba that is nineteen years older than the machine you show, and while parts can be challenging, the machine is well worth the effort.
You cannot buy a dishwasher as good as the old KitchenAids today, no matter what you spend.
Hanging out here has one huge bonus - we have KitchenAid expert stevet as a member, who knows stuff about KitchenAids that KitchenAid itself forgot a long time ago. He is ever-helpful, and a damn nice guy.
It all really boils down to how important having a really capable vintage dishwasher is to you, as opposed to one of today's "eternal sprinkle" machines. To keep an old KitchenAid going, you will almost certainly need to become your own service tech, and you will need to become resourceful when it needs attention. But you will be rewarded with cleaner dishes, in less time, than is possible with the puny equipment being sold nowadays.