i think the demo map for this tutorial has what u're looking for (its a great tutorial anyways)
http://world-editor-tutorials.thehelper.net/multiboard.php
i have this sell trigger and it says you have recieved x gold for selling a custom_h00(random letter).
sell
Events
Unit - A unit Starts the effect of an ability
Conditions
(Ability being cast) Equal to Sell
Actions
Player - Add...