Sadly, Apple doesn't see parts for the Trackpad. Your only hope is to locate a junker to steal the parts.

The feet are a bit tricky here, as in the middle is a small pin that offers the click feedback and the click button function (Left & Right) so you really can't just throw on any self adhesive rubber foot on.

Basically you need the special rubber foot. Here's a good guide on how to replace the foot: Magic Trackpad Rubber Replacement/Reinsertion