actually, sunscreen tends to be expensive in the states.....that is, expensive relative to other toiletries....i'm not sure why....
so i would doubt you can save much money (as you usually can on other things)...
but if you don't have the room, i suppose you could wait....but really....how much space does a bottle of sunscreen lotion take?
the key is that you HAVE to use it....we see so many fried Brits when we're in Florida.....they're so obviously British, by the deep red color of their skin.....it's painful just to look at them....
remember that the Florida sun BURNS....and does it very quickly...
we always bring ours with us, mainly because we like the local brand much better than the american ones....in fact, i just went out to buy some for the trip.....
given that you really should put it on almost the moment you get there, perhaps it would be best to at least take some with you...