In 2003, Odyssey decided to go a step firmer than the White Hot line with their insert technology. They released the DFX line, consisting of 10 club models in the low $100's MSRP range. The heads appear to be carbon steel, coated in a grey teflon or paint. The inserts were glued in with a significant amount of epoxy, concealed with a white border applied around the edge.
Today, there are many great deals to be had on ebay.com with these clubs. Some are seen as low as $15, so they make great candidates for optimization & experimentation. The inserts are easy to remove with the boiling process. The coating/paint can easily be blasted off. The toughest chore is removing the epoxy from the pocket after the insert is pulled.