Best for the money (expensive though) is vibraplane. See
You'll find lots of discourse by searching for shelves, isolation, etc. I continue to be VERY happy with my Neuance iso/absorp platform shelf under my CDP. Clearly a tighter, more coherent sound than air suspension or cones-alone.
Good Luck. Ernie
PS You may wish to address Redkiwi or Caterham directly re experiences and theory of operation.
I will second the Neuance shelving, which I support with upturned spikes (built into my rack). Very even handed without the annoying dips and peaks that I always seemed to get with my previous isolation methods. The music also has a better pace to it now. It is very simple as I just rest my components (with their stock feet) on the Neuance shelves and no longer have to concern myself with gear toppling off of cone points and such.
I think the type of isolation platform you wish to purchase or build would depend on the type of vibrations you wish to eliminate. If you wish to eliminate room born vibrations then I belive you need some type of air suspension system. If you are looking to isolate chassis vibrations then some type of cone/sand loading may be better. I have my SFCD-1 resting on 10 pounds of sand which is contained in four zip-lock type plastic bags. The sand then rests on a piece of MDF shelfing supported by a 12 inch inner tube that is partially inflated. On top of the player I have about 5 more pounds of sand again contained in plastic bags. This works wonders for me. The total cost of this system is below 10 bucks. good luck
I've just installed a Neuance Shelf under an Accuphase DP-75, which at 43 pounds has some vibration control built in. The improvement was striking, and while I love to tweak I don't expect to try to improve on this arrangement. It is important to get the underpinings right, and Ken Lyon at Greater Ranges (the Neuance company) was endlessly patient and helpful to me in planning a DIY spiked platform.
I feel that there are two types of vibration to be dealt with. The first is internal and is what is produced by the component that is being isolated. This is what you want to drain off quickly and "evenly" without creating dips or peaks in the frequency response. The second type of vibration is external (which includes air born, wall and floor born and internal vibration created by the surrounding components that will try and make it's way into other units via the equipment rack, etc.). The second trick is not allowing this external vibration to enter your components. Cones work well to drain off vibration and soft footers work well in not allowing vibration back into the component so many of us use platforms that entail soft footers/a wood (Maple) or other platform/downturned cones (coming from the unit). I have had good results with these types of platforms, however I never felt that I was able to achieve an even frequency response without dips and peaks (not saying that this cannot be done, I was just never able to do so). Another thing to consider is that when better components are designed they are voiced with their stock feet resting on some sort (?) of shelf. There was obviously something about the sound of the unit that attracted us to it in the first place (although we are attempting to fine tune things a bit) and once the stock feet are removed from the equation the sound generally changes drastically. It seems to me that I spent most of my time with cones, platforms and footers trying to get back to this original sound, though again, with a little fine tuning/improvement. What I like about the Neuance shelving is that my equipment maintains its inherent sonic signature, but it sounds better (fine tuned) with improved detail, much improved pace and rhythm and the frequency response being more even (sounding good on a wide variety of source material), the equipment rests on its stock feet on the shelving. Have I measured the frequency response? No, I have not, but I can hear it when playing a wide variety of music. I experimented with the cones and such for a six month period and did become experienced enough so that I could pretty much fine tune parts of the frequency response by moving them around under the bottom surface of the transport and DAC. I could accent the bass, the mids and the highs (which can be very flattering to a particular type or piece of music), but I, once again, was never able to get it right (to my taste) over the full spectrum and often would loose the sonic signature of my equipment with the playback being to bright, too thin, a big peak in the mids (great on some vocals, but lousy on classical) and on and on. As a reference I would always go back to the component resting on a sturdy shelf on its stock feet and from there would start tweaking all over again. I suspect that what I was dealing with is that the cones, footers and platforms all had their different frequencies that they boosted/favored (both sides of a boost can also be taken as a drop out, it all depends on how you look at it:-). Anyway, it was a lot of fun, but never really got me to where I was going and I much prefer this simpler approach (simpler for me as I did not design the shelving) in both sanity and sound.
As a strong proponent of the school of thoughts that says that, since vibrations can't be dampened evenly throughout the spectrum, thus resulting in the cure being worse than the illness (please refer to Decay's post mentioning "dips and peaks"), only way to deal with them is to drain them off as fast as possible, without intefering the resonance characteristics (now, this is the most complex part). Whatever worth my experience on the subject, Neuance seems to be the most complete solution I've come across. In some particular cases rollerblocks or cetech carbon platform (only with their cones!) may be used to a good effect, thus some careful matching is mandatory. Same works for all sorts of cones as standalone cheap solutions.
p.s. sorry to dissapoint those advocating for the use of air pillow type of devices. Sure, they are used for placing very precise optical microscopes. Only, regardless how much I try I am continuously failing to understand what would an amplifier or turntable or CDP have in common with a microscope...