I think this is probably one of the most viable business models for a "CubeSat" sized payload. If I had a rocket to the moon, that is the first thing I would offer: "mix your human dust with moon dust"
Figures above suggest somewhere in the million dollar mark for a kilo of payload. There are ashes into diamond services, and ballpark figures would be 5 one carat diamonds to a gram or 2500 for half a kilo.
A million dollars split between 2500 is just $400 each.
Obviously very rough figures but it nothing screams outrageous to me. I'd be surprised if you couldn't fill 2500 of those orders.
Only problem I see is that 0.5 carat cremation diamond is $6000 US, and it would be a "waste" of the ashes since they only use a few ounces (~150g) and a human cremated is roughly 5kg.
BUT, if a person is fine with only sending a portion of their loved one to the moon for the super "low price" of $20k, it would only take 75 to break even, but there is room for a WHOLE lot more.
Space burials [1] are a thing. When I investigated this, I found that in Germany the cremation industry is against separating remains, i.e. don't bury a part on Earth and another on the Moon. I'm not aware whether a legal background exists, but at least some might consider it as morally dirty (though I doubt people would really complain over here, but in other cultures people might react stronger). So it depends on your country (culture, jurisdiction) whether it's a viable business case.
I can imagine some rich people would find it pretty cool to have an urn of their ashes left on the moon.