As someone who has done this for years and goes to the countries themselves, if you can get the exchangeable coins in bulk for at least 65% of the exchange value on popular countries (euro, Canada, CH, etc) then hold onto it and trade it for other countries/coins you might want. If you are going on a trip to Japan for example and have someone who is willing to give you yen for francs, then you will have essentially given your trip a huge discount! Just a few months ago I had exchanged some 800 CAD in coins that I had accumulated for pesos and Swiss francs, and now I have another 400 ready to trade again. Since I do this a lot, I have a mental note of what coins are worth picking out and leaving, which are redeemable and have no value; if I am unsure, I multiply the weight of the coin per pound with the price per pound, and compare with the exchange value. Getting exchange coins might encourage you to visit countries you would not have considered before; I do not think I would have prioritized visiting Croatia before had I not accumulated all the kuna before the deadline. It is a fun way to recycle money with no collector value that otherwise would have been sitting in a box or bucket forever.
