Walmart offers the Pyle 9" x 12" Acoustic Sound Isolation Dampening Recoil Stabilizer Speaker Risers 2-Pack for $23.04. Choose in-store pickup to avoid the $5.99 shipping fee. (Amazon charges the same with free shipping for Prime members.) That's the lowest price we could find by $3. They help promote the flow of "clean" sound projection and reduce vibration and unwanted audio resonance.