Products like that and the subdude or gramma are just a rip off. If you know friends working for a software company, ask them to get you some of those dark gray foam used for PC packaging. My company buys a lot of PC equipment and I see those foams thrown away along with the box all the time.
I use the rubber feet from MCM Electronics. There are many sizes. Dont get ripped off by products like isolation pads, subdude or gramma or granpa or any such gizmos. There is nothing special about them. Just regular foam/or cork and some MDF. You use special material only for space applications :-) See my DIY subdude at the Auralax thread. That is pretty much what they sell for $50!