Its a bit of extra work, but
Odric, Lunarch Marshal can give all your creatures haste as long as you already have something with haste on the field.
Haunted Cloak gives haste that can be moved from creature to creature for 1 mana if you are just after giving one creature haste.
Spontaneous Artist can at least theoretically give all your creatures haste, although you would need to build around energy to make it effective.