Rereading the preceding section on Androids it seems that the cost per base slot is also multiplied by 3 so it looks like the body part of the Zombie would make up the majority of the cost at KCr96.
Zombie (TL11)
Size 5 Biological Robot (basic) - KCr96
Basic (Labourer) - TL10 Biological Brain - KCr12
Default Suite (Visual Spectrum Sensor, Voder Speaker, Auditory Sensor, Wireless Datalink, Drone Interface) - KCr0
Olfactory Sensor - KCr3
Transceiver 50km (enhanced) - Cr750
Total KCr 111.75, so rounding to 100 would be logical.
I am not sure why the Zombie has only 3 Spare Slots, it should be 4, so there could be some other factors involved or it could just be a typo.
Since they are basic biorobots they are not going to be able to pass themselves off as sophonts much of the time, so the justification for building a biological robot with the limited capability of the Zombie is unclear.
Unless you can find a free body the Zombie is not at all cost effective. You would be far better building cheap clones or just non-biological labour droids (at KCr5 each).
Even if you could save the KCr96 for the body and trim off some of the more exotic equipment (do you need a built-in transceiver of that range and a sense of smell may be a luxury), just the basic biological brain is still more expensive than alternatives.
The only value in my mind is the actual deterrence from your population knowing this is what happens to criminals/dissidents. That might be worth a few credits, but not KCr100.
Just buy a much more capable labour droid and drape it in the flayed skin of executed criminals instead