Raise the "Development Level" of one of the Titans to 5 Star through "Salvaging" and "Exchange" (Torigoth preferably). This can be done by buying as much Silver Cylinder as you can, salvage it all, then exchange them for G (money). Repeat til Development Level for said Titan is at 5 Star. At 5 Star Development Level, purchasing price (5 Star Titan) is identical to sell back price (any other Titan). Now purchase 99 stacks of Normal, Silver, and Gold Cylinder (doesn't appear til after you finish Ch.4) from the 5 Star Titan you already have and sell them to a different Titan that you want to develop with no net loss. Repeat til Development Level is at 5 Star.