There's also the Vivitar 75-200 Autofocus lens...
Vivitar 75-200mm f4.5 Autofocus (Cosina?) Lens Reviews - Vivitar Lenses - Pentax Lens Review Database
Yeah, not the same as the Series 1
But I can vouch for the fact that it will autofocus on a K1000...
Something I did mean to mention in my earlier post is the Pentax F70-210 (not the Takumar one)
It is an autofocus lens, so the ergonomics are pretty sloppy on a K1000 (and unlike the weird Vivitar above, it will not autofocus on a K1000), but it's optically solid and it works a treat on the modern digital cameras as well (and of course, older Pentax AF bodies).
-Eric