I often buy some gifts for my friends on special occasions like their birthday 、anniversary and so on.but ,I won't buy something very expensive.because more expensive the gift is more sincerity it contains.so ,I usually buy some gifts that fit my friends' hobby.usually ,second-hand book always a good choice.because most people have their own favorite book .we just need to find out the book and cost couple of pennies .and that is what will bring the happiness to your friend .
of course ,the gift shouldn't too costly.but none gift is an unadvisable idea.anyway,your friendship should base on some realistic stuffs instead of verbal promise.