United Airlines has cheap flights from Dallas (DFW) to Ho Chi Minh City (SGN) available for $783 round-trip. Itinerary has two layovers. The fare rules have allow stopovers for $100, which will probably be easiest to score in Japan or Hong Kong.
[09/24/2014 @ 6:24 PM] This fare has dropped to $842 was $910 during original posting.
[10/17/2014 @ 8:33 PM] Re-added to bookable list. It’s now priced at $783.
[10/30/2014 @ 8:19 PM] Most fare availability is gone.