The storm one can't be upgraded, but does more then the fire at the start, and the flower one costs 3000 for it's first level, but does as much damage as the fully upgraded earth one.
The flower one also sucks. As you upgrade it, it's range decreases, and the creator has "tweaked" the game so that it's rate of fire is slower. It doesn't hit for sh*t, and is therefore a waste of my 8000 gold to get it upgraded once! Though it should have done 15k damage, it never hit. Grrr!
Also, 73 now...