Isolation feet for monitors


I need to isolate my Linn Katan monitors from the bookshelves that they currently sitting on.
System can be viewed here : http://forum.audiogon.com/cgi-bin/fr.pl?vopin&1095824323&view
I have placed a 12”x12” slab of granite between the speakers and the shelves for mass, but now need some sort of isolation footing to separate the speaker from the granite.
A cheap solution would be to insert some neoprene pads beneath the monitors. Has anyone tried this?
Another option would be isolation feet or spikes. Are there any cost effective suggestions for feet?
Thanks
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I have Soliloquy 5.0 monitors and I've tried many things underneath them. The best by far are #2 Vibrapods. Enhanses the deeper bass and its definition and tunefulness. Clarity and microdynamics are also excellent.

I also achieved very good sound with Small Isonodes by Bright Star Audio. The ultimate in clarity, but they did suck up some of the microdynamics. Fleshes out beautifully though when turned up.

Mine are almost 4' from the back wall however. Yours look to be pretty close.

Chris
Wearherstripping is what I have used under my monitors on a number of different platforms. It's real cheap too. It comes in different densities and thicknesses. It's worth a try.
I'm curious why you feel the need for isolation. Any type of flexible feet will allow the monitors to move about. My experience with monitors is that the more rigidly they are held in place the better they sound.