The heart of the Spud is the US made iron. This consists of custom wound output tranformers and a stock power transformer made by Edcor. Since the intro of the Spud in 2007, the iron price has more than doubled. Additionally, the passive component prices have all skyrocketed as well. For example, the current Alps potentiometer is 5x more expensive than the former potentiometer used in the kit. Instead of sourcing cheaper parts, I decided to continue to source very high quality components, but that means I am forced to grudgingly pass on a small increase to buyers. With a bill of materials that includes Edcor, Alps, Nichicon, Vishay, Dale, Belton and other high quality parts, the upgrades are already built in.