This may strike you as an odd/disturbing question. But, nevertheless, I am quite curious what people think.
Here goes:

How much money would someone have to pay you for you to cut off your left pinky finger? Would you do it?
Could you do it?

Here are some guideline-ish things:
You may not use the money to re-attach the finger.
You must cut off your own finger using a knife.
EDIT: Except for the removal of your finger, you would not suffer any other damages from the injury. (i.e. infections, blood loss, flesh eating viruses, ect.)