If you have only one or two cameras, then Jon Goodman's kit is a good route. If you have a lot of cameras, I would recommend Foamies. One sheet is a couple of dollars and will handle maybe 50 or 60 cameras.

You can cut odd shaped pieces without worrying about running out of product. You'll encounter this situation with some of the Japanese rangefinders.

For $4 or so, I've refoamed about 60 cameras in the past two years. Very economical, compared with $10 a pop for each camera ($600).

Although I can't yet prove it, I believe this product won't turn to goo after a decade.