I just finished this quest chain and received an in-game mail:
"Dear Contract Worker,
It has come to our attention that one Greblin Fastfizzle recently employed your assistance in recovering a number of artifacts from northern Nagrand. After an exhaustive review of his receipts and invoices from this expedition, we have determined that his monetary valuation of your rescue from his malfunctioned glider was improperly high. Therefore we have issued a refund in your favor.
Sincerely,
Your friends at the Steamwheedle Preservation Society Board of Insight and Inquiry
NOTE: By accepting this payroll adjustment you forfeit your right to future arbitration or dispute on this matter."
The letter also includes [item=119128] worth 500g