Walmart offers the Gold's Gym Adjustable Cast Iron 40-lb. Dumbbell Set for $29.99. Opt for in-store pickup to dodge the $5.99 shipping charge. That's tied with our mention from three weeks ago the lowest price we could find by $8. The set includes two 3-lb. handles, four 2.5-lb. plates, four 6-lb. plates, and four collars.