Amazon offers Prime members the Lava Heavy Duty Hand Cleaner with Moisturizers 5.75-oz. Bar 2-Pack, model no. 101861, for $2.17 with free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping adds $5.55.) That's the lowest total price we could find by $7. It contains pumice.
Note that this item is currently backordered, with an estimated shipping date of two to five weeks.