X-no-Archive:yes
I worked on another platform that used its native scripting facilities for
scheduling. What was clever was that the system start routine started two
such scripts. A monitor script made sure that the scheduler script was
running / scheduled, and the scheduler script made sure that the monitor
script was running / scheduled. It was assumed that it would take something
of a more catastrophic nature for both to die, and the catastrophe itself
would not go unnoticed. Nice bit of hackery, and it seemed to work.

We use Nobix JobPak, which may or may not fit your definition of reasonably
priced. I am surprised that no one mentioned MasterOp, which is free.