i gave my priest (OO) once some anointing oil (mir / myron) from a romanian (EO) monastery.
he was really pleased with it!
ok, so u have to be passing by a church that sells monastery oil, so it may not be convenient.
otherwise chocolates are fine.
if you have a computer but no money, you can print out a really beautiful icon, personalised with some writing (typed if you are really good at the computer) from you at the bottom.
we copts range from the stingy paper-icon types, to the (awful) bling flashing light ones!
(u can guess which one i am!)
it is less common to give gifts in OO churches generally, so don't take my money-saving solutions too seriously for an EO priest.
if u have lots of money but are not sure what to get, then maybe get a small gift (e.g. something edible for the family) and put the rest of the money in the church box on sunday.
ok, so i am rubbish at gifts.
the last gift i got my God mother was an icon style fridge magnet, don't copy me too much.