The Crayola website claims they make 120 standard colors and some specialty crayons.  Thus, you'll only get the 120 color box.  I say buy the 150 crayon tower (which appears to have maybe 50 different colors the rest are repeats) and dump all those in the trash, buy the 120 color crayon box to fill the tower, and then hunt down those specialty crayons to fill the remaining slots.
Or, if you are willing to go generic/store brand, their colors won't match exactly.  Thus, you suddenly have many more colors to choose from.