There are only two ways to make money on currency arbitrage:
1) put several hundred thousand dollars into the market split between bet currencies, those you believe will move up or down significantly, and hedge currencies to flatten the downside curve;
2) run the currency like Soros did in several Asian markets early last decade. That takes several hundred million dollars
As to the Iraqi dinar, your friend is SOL. As an oil currency , it is either indexed directly to the dollar or a dollar/Euro-heavy basket of currencies (I can't recall which), therefore it will never substantially appreciate against the dollar. Interest rates may be high on the dinar, as will inflation, but the incremental on $3000 worth of dinar are negligible. A sofa hunt for coins would deliver greater yield.
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