This should never be the case for something you get off the element picker. If it becomes mandatory, it restricts choices and removes strategic depth. As I mentioned in the other thread, this might be better suited for one of the available "super weapon" picks as a more passive/economic option. Constant reselling seems to me, to be a measure of how much mindless tedium one is willing to put up with. The game has some strategic depth, and I am saddened that the "optimum" method is gaming the system with as many resells as possible. Why even have such a variety of towers and combinations if this was the prime direction of the game? If spam reselling is the prime strategy, one could probably suffice with only the basic ray and grenade towers.