In Skrill I have been able to send as low as $0.01, they don't have a minimum like some other payment processors.
I doubt that because there is a fee that is taken off more than 0.01$.
I sent what I had in skrill account and could not send entire amount in the account because of that fee.
This was just a test phase for the buyer. And I sent all I had in my account now it is empty.
If they want to trade anymore then reply to the thread he might want more cause I sent what I had.