I was in exactly the same situation on my flight to SIN earlier this month. I bought my ticket in July, and I had a $600 bump voucher. The best I could do for a non-web fare was $754 (and that was from LAX). Thus my final cost was $154. The cheapest web fare at the time was $572, so had I been able to use the voucher for that, the flight would have been free!

Good luck, but I don't think you'll find anything under $750 from DFW.