Walmart offers the CAP Barbell 40-lb. Cast Iron Dumbbell Set, model no. RSWB-CS040T, for $24.99. Opt for in-store pickup to avoid the $4.97 shipping charge. That's the lowest price we could find by $30. It features four 6-lb. plates and four 2.5-lb. plates.

Also available is the Sunny Health and Fitness 40-lb. Vinyl Dumbell Set, model no. NO.060, for $24.21. Opt for in-store pickup to avoid the $4.97 shipping charge. That's the lowest price we could find by $19. It features three adjustable weight tiers.