Are you saying that you believe that there is no way for you to manually set your fee when you send bitcoin? Would you like to wager on this?
It is of course possible to create a transaction with any amount of fee that you want it to have.
Thanks for killing my action.My only issue is that if I say "send my transaction paying 300 bits for the fee" and you send the transaction with 240 bits for the fee, that rubs me the wrong way. Even if the transaction gets confirmed in the next block. It's the appearance of impropriety. Even if 240 was all it took, and even if sometimes you charge me 300 and you spend 500, if I say "use 300", you should be using 300.
It seems to me that a better way of doing it would be to say "do you want this medium priority or high priority" and showing the average fees each option takes, and then deducting the exact amount of the fees you pay (as directed by the customer) from the withdraw.