Damping Plates

I want to be clear, I'm not saying all or even any of these things are the way to go. I'm saying trying them is an experience that will help you learn to evaluate and select the really good stuff. 

Very little of what's out there is sophisticated, in that the properties are inherent in the material. That would be something like the carbon fiber and resin material in BDR Shelf and Cones. Inherently dense, very stiff, and highly damped. Its very rare to find something so across the board excellent as this. More often its combinations of compromised materials. VPI laminates acrylic and aluminum, for example, and lots of people laminate wood, or combine metals and elastomers. All they are really doing is what I did with my rack- combining different flawed materials in an intelligent mix that combines the best of each in a way that balances out or covers up each others weaknesses.

What I'm really saying is this is something everyone can learn to do. 

Fo.Q tape.

Start here.  End here.

millercarbon, I guess you did the best you could do with what you have. You cannot be penalized for that. As McMurphy in One Flew Over the Cuckoo’s Nest sarcastically says to the inmates after he was unable to lift the 300 lb water cooler, At least I tried.  🤗

“I’m saying trying them is an experience that will help you learn to evaluate and select the really good stuff.”

One of the very few posts by millercarbon that is spot on...LOL. 
Most of the isolation, dampening accessories comes with return policy. I encourage you to try as many you can in your system and keep the ones that makes the most audible improvements.

HRS dampening plates are very effective and elegant, thus earns my recommendation but like you said, they can get expensive.

On equipment with contiguous top plates (no exposed tubes)  I spray painted 2.5 and 5 lb. bar bell weights and glued a thin cork sheet under. 

The brass damping weight mentioned by lowrider look nice and come with cork or some type elastomer base. For equipment with exposed tubes I would want a base that keeps these weights from slipping.