Using 90/10 split: that 10% of the time before being reduced to only take 10% of that makes 9% time savings. 160 hours a month * $100/hr programmer * 9% = $140

Using 90/10 split: that 10% of the time before being reduced to only take 10% of that makes 9% time savings. 160 hours a month * $100/hr programmer * 9% = $1400 savings, easily enough to justify $200/month. Even if 1/10th of the time it fails, that is still ~8% or $1200 savings.