Charging for Product Updates

I have lots of toys and gadgets that needed updates after H4... and so far three people charged for them. in one case it was fully justified because the new version is a complete remake with totally different sailing characteristics (Flying Fizz 1.0.x versus 2.0.x). In one of the other cases it was moderately justified because it was not that much, and it was more like a handling fee as compensation for the third person who did the manual updating... in the third case it was a bit too much in my optinion.