OK, sorry, I'm an idiot! I just realized the TRE doesn't run on Sunday. That pretty much leaves your options to renting a car or taxi to d/t Dallas or Fort Worth. I'd estimate @ $60 each way for either city. Not attractive, but this an extremely automobile-centric area.

DART in Dallas www.dart.org or city buses in Fort Worth www.the-t.com would still get you around either city if so inclined. A taxi to Grapevine Mall should be much less expensive, $20 or so each way. Again, feel free to PM with any more specific ???s