Find a local engineering parts supplier and see what bushes they have - you'd be surprised what they'll have. Even your nearest fastener supplier may have some anti-vibration bushes that will fit.

I've used these guys over the years for one-offs and odd applications, obviously they're based in the UK, but they're good at what they do...

http://www.polymax.co.uk/Anti-Vibration_Rubber_Mounts/

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