I'm a big fan of army building so how about 7-Packs of:
Range Vipers (They could even make specific theaters, such as desert, forest, etc.)
MARS Forces (Iron Grenadiers, Annihilators, TARGATs)
Alley Vipers
Any of the Collector's Club exclusive sets: Crimson Strike Force, Coil, Skull Squad. Yeah, they'd lose their hipness appeal, but mass producing them may lower their prices, then we'd all be able to enjoy them.

Not the most original idea, I figured it would help us grow our Cobra forces.