I've done this about 4 times with a 50% success rate.
I send a mail to someone I find in a battleground who is obviously botting that they have been found botting and I will report them and threaten that they will lose all their recently purchased gear / tokens / etc and may even receive a perma ban.
I then add that for the sum of 100 G I will completely forget about ever seeing them and they can continue botting away.
Worked twice, as I said... and just logged in to 200 gold awaiting in my mailbox.
I can upload some screens later of the exact mails