You’re not wrong Alan. I have two loco projects in boxes ready to build with all the ‘rare’ bits already purchased and laid by. When I am planning a loco I buy wheels first, then distinctive, characterful things like chimneys and domes. That way I know it’s all laid by ready. Given how long it takes to build a loco, by the time you’ve gone from chassis to superstructure your favoured supplier may have stopped trading.