Double Bulk Pricing with Rain Check wins every round, and also adds the entire total (-$10) to your budget
It also takes up less space than Bulk Repackaging with Flash Sale + a Double Coupon Day, and is much cheaper to build
Although, both of them together leave a space for an Infinity Round, and that is a stupid level of greed lol. Loved to play this strategy, got to about round 50 and 5k budget.