Best levels for stockpiling money

It seems to vary. They're not all the same every time.
I know definitively that 'easy' are 10k.
Moderates are about 50k I believe. I'm not sure, but I'm doing one by myself next week, so I'll find out then!
And my club figured out that perk 7 this week is either 200k or 225k (leaning toward 225), but perk 6, which was also very hard, was only about 150k.

That said, all 7 perks this week combine to 700k.