Byrd - I've solved the expense problem by running over the main line, then purchasing a whole new line and keeping the extensions from the old one. Can't lose...
Seriously I have friend that swear by using 1ea. 5' poly e take off (from an old ski rope, the stretchy kind). They say that there is only a slight amount of stretch in 5', and that it is less painful to the arms/joints on tricks where you get jerked on landings (tantrums).