There isn't $150 per mobster, but it is $250. This was done to quell the fact that a lot of money can be won really quickly. It was known that the tree was going to change after a few episodes, so it shouldn't be too much of a surprise. This is the new setup:
1 - $100
2 - $250
3 - $500
4 - $1,000
5 - $1,500
6 - $2,000
7 - $3,000
8 - $4,000
9 - $5,000
10 - $6,000
11 - $7,500
12+ - $10,000
I like it, personally. It makes for longer games. Also, the idea would have been present that a contestant would've had $100,000 on only the fifth question, not wanting to risk it, but that's nearly been eradicated.