I think the decision on whether you take it with you or purchase it there should be made on the cost of the film in the two places and on whether or not you'll buy too much film to schlep through airports. On a recent two week trip to Europe I took about 20 rolls of 120 with me. In my carry-on bag, it passed through xray machines at Pittsburgh, St. Chapelle in Paris, the Paris airport, the Milan airport, the Paris airport again, and the Atlanta airport. Speeds were 100, 320, and 400. The film was unaffected by the xrays.

As long as you don't mind carrying your film with you and your speeds top out at 400, I wouldn't worry about buying it before you leave. Given the current exchange rates, you might save some money by carrying your film.