Grid Charger Differences 1G vs 2G vs 3G vs Insight, etc

I've noticed some pretty significant price differences between grid chargers.

Maxx Volts 2000-2006 Insight Grid Charger is $150.
Maxx Volts Lexus CT200h grid charger is $389.

Are there differences in Power Supplies?

Prolong is the same way:
Insight $359
Prius $409

Both appear to use the same power supply, different harnesses, obviously. I would assume this is partially because the Insight doesn't have a battery cooling fan, in most cases it looks like the harness-to-power supply "plug" looks the same, so its probably just the same power supply with different harnesses.

Anybody know why there are such big differences in prices between these products?