Hi,
If you think seriously to invest in other country -no matter in which commodity- then you need to consider the following point.
Exchange rate
You have to study the fluctuation between your country currency and the country you intend to invest in. By saying 'study the fluctuation' I mean in the past and expectation future.
Personally, I've purchased an apartment for letting at 2011 when my base country currency was 2 times the investment country and it was around 7% annually but after around 4 years their currency starts to deteriorate due to economic difficulties which brought my return to about 3.5%. I know it is impossible to predict the future but keep this point in your mind and make further readings about the country you wish to invest in.