Best to ask past travelers how much they spent. In some cities, Paris and Madrid for example, mass transportation is a bargain. Your lunch supplements on certain semester trips will not buy a sit-down lunch. This can really add up. Post cards are costly, stamps no bargain.
Aerograms are the best deal.
I. FILM Best bought here and in bulk. Check mail-order companies. Processing overseas is expensive. Pictures make great, low cost souvenirs. Plan ahead .