Walmart retail stores offer the Cascade ActionPacs Dishwasher Detergent 20-Pack in various scents for $3.97. (The link is for reference only; you must complete this purchase in-store.) This $5 mail-in rebate yields a net profit of $1.03. That's the best deal we could find for a 20-pack after rebate by $2. Rebate is limited to one refund per household and ends December 31.