My thoughts..

[Cassie]

That sounds about right, except I think it should go up to 6+ and have about 90/100,000 Simoleons. But these are definitely much, much more reasonable.

Or maybe there should be an option, from 20,000 Simoleons to 100,000 Simoleons that you could use to decide how much of a challenge you want? You should only be able to chose from about 50,000 Simoleons onwards if there's 6 or more in the family.