Depending of what you want to get for them and if they support any team in particular ie team tops and hats would be good gifts or model F1 cars is another suggestion tho' it may be late in the day to get them in time for the 25th. E-bay seems to be a good place to choose what you want with a huge choice or you can just go direct to shops like Jos Verstappen.com who leads this field in Europe. I heard F1 stuff is super expensive in the States.
GL