Foil/Mylar balloons in many versions, like figures/characters, round/hearts/stars with print, round/hearts/stars without print, large letters or numbers etc...
An advantage of foil balloons is that they float for 1 week or longer with helium, notice though that the prices below are without helium!

The prices below is without helium!

Important: Cold air causes balloons with helium to shrink, but expands nicely again at normal temperature ... Very high heat increases helium emissions!