On a trip to Las Vegas from London, CPA Dan Morris once saw professional poker players from London carrying cash for a $40,000-fee tournament.

Me? I wouldn’t even wear my wedding ring anywhere for fear it would be stolen, never mind when traveling.

It just goes to show that our perceptions about money are relative. While $40,000 may not seem like much to a high-roller, traveling with that kind of cash would make me sweat bullets.

Imagine the customs-declaration forms for those gamblers -- 10 grand is the minimum amount for having to declare your cash with customs. If you're carrying $10,000 or more, your money is tracked to see if you're involved in an illicit activity.

Every time I travel outside of the country, I look at the U.S. customs declaration form and wonder who's carrying $10,000 or more in U.S. currency or the foreign equivalent.

And it always makes me wonder if someone could make money off exchanging $9,900 in currency outside of the U.S. and then exchanging foreign currency when they return, thus making a profit.

But Morris warns that investing in currency while overseas can be a risky venture. Here's why.

It's Hard To Keep Secure

Let's face it. Carrying a load of cash is risky. As an alternative, it's only $1 or so to use your ATM card to withdraw funds from an ATM machine. You can also use your credit card most of the time.

You Have To Have A Paper Trail

You may save money on currency exchange, or even make money, by getting currency exchanged at a place outside of a bank in some foreign countries. However, the government may ask for paperwork when you leave that shows where you got the funds. If you can't provide it on the money you exchanged, you may get accused of counterfeiting cash or doing other criminal activities. Morris says it always seems when he arrives in Europe that it costs $1.40 per Euro on the way in and $1.30 per Euro on the way out. He'd lose money exchanging too much currency on the way in. But if he sees a great exchange rate, he may stock up just enough for cab fares for his next visit.

Transactions Add Up

If you're bringing back $8,000 on a regular basis, any reputable place exchanging the money for you will track it and send your info to the local government. If you do this several times per year, you're going to look awfully suspicious. The only exception is if you have a home overseas.

The Investing Answer: There are two times when investing in foreign currency makes sense. By simply investing in the Forex foreign exchange market, you can safely and without suspicion of criminal activity profit off the highs and lows of the difference between the price of one currency versus another. Forex investments are very common, but it's always best to talk an advisor who follows currency differences so they can help you figure out when it's best to invest in specific foreign currencies.

The other time is when you're a frequent traveler and notice a really great exchange rate. Put aside $1,000 or so and deposit it in your bank so you have money for taxis, dinners out, etc., at a nicer rate.