Shelf for Preamp Power Supply?

My system consists of Thor TPA-150 monblock tubed power amplifiers, with a TA-2000 tubed preamp, with Quad 988
loudspeakers. The system rests on Sistrum racks. I am planning to upgrade my Thor preamp by purchasing the MK II
versions of the Thor Ta-1000 linestage and the Thor Ta-3000 phono stage. I also use a VPI Scoutmaster turntable.
In any case my system sits on audio points, which is fine for most components except for turntables and in my case putting the two power supplies on the same shelf. Therefore, I need a shelf to place on the points about 19 X 15. Thre cost of the black diamond shelf or board in this size is anywhere from $600.00 to $800.00. I know I'm spending much on equipment, but is there a cost effective way to minimize vibration? Robert of Star Sound Technologies recommended that I purchase copper or stainless steel as they would work better with the sistrum racks which are metal. Any cost effective leads in any material? Thank you for your responses.
You can contact Mapleshade:888-2362753.Their 18" x 15" platforms run $155.You should be able to order a 19 x 15 platform and get it 4" thick for alot less.