OK, I have just worked it out, and for immediate benefit, it is best to Counterfeit a Counterfeit rather than Counterfeiting each Bank separately:
My hand consists of just 2 Counterfeits and 2 Banks.
Option 1:
-Play Counterfeit, get +1 Buy and $1, choose Bank; total is $1
--Play Bank, get $2 (Counterfeit, Bank in play); total is $3
--Play Bank, get $2 (Counterfeit, Bank in play); total is $5
--trash Bank
-Play Counterfeit, get +1 Buy and $1, choose Bank; total is $6
--Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $9
--Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $12
--trash Bank
End result: 2 Counterfeits in play, 2 Banks in trash, $12 and 3 buys
Option 2:
-Play Counterfeit, get +1 Buy and $1, choose Counterfeit; total is $1
--Play Counterfeit, get +1 Buy and $1, choose Bank; total is $2
---Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $5
---Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $8
---trash Bank
--Play Counterfeit, get +1 Buy and $1, choose Bank; total is $9
---Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $12
---Play Bank, get $3 (Counterfeit, Counterfeit, Bank in play); total is $15
---trash Bank
--trash Counterfeit
End result: 1 Counterfeit in play, 1 Counterfeit and 2 Banks in trash, $15 and 4 buys
Net immediate benefit of $3 and 1 buy.