Do you come from a country where they pay you to donate blood?
If yes, is that the only reason you donate? Would you continue to donate if they stopped paying?
If no, would you ever accept a payment for a blood donation?
In Australia a blood donation is exactly that, a donation: no money exchanges hands (although they will give you a cup of tea and some biscuits). I find the idea of being paid for my blood a little bit creepy. To me, getting paid for what naturally grows in your body makes a charitable act a business transaction. What are your thoughts?