At this point, I say the Cowboys should just stick with the WR core they have, and should work Turpin into the slot more (finding some plays to get him the ball in space, like WR screens or the jet sweep, or whatever...Moore, FIGURE THIS OUT). Turpin played WR in college, so they should get him involved in some 4 WR sets and make him a threat. Hec, send him deep from the slot sometimes and make the defense respect his speed, and then run some WRs underneath the deep route. It's time for Moore to get creative with someone who obviously has the speed to scare defenses.
Forget OBJ. Wait until the season is over, and upgrade at WR during the offseason in the draft or in free agency. If anything, the Boys may need to find a CB before the playoffs start.