Morgan,
I lived in Hungary and also did a lot of traveling throughout the Transylvania region of Romania. You can find this type of canteen made new for the tourist market but you can also find originals in plenty of antigue stores in the major cities or the average weekend markets that only locals would know about. Are you looking for a value on it or just curious as to whether it may be original or not?
The colors are typical for the entire region of Hungary, Slovakia, Transylvania and western Ukraine. Pretty much anywhere that fell within the borders of Hungary during the Austro-Hungarian empire.
And, yes, they would have been common to Hungarian "cowboys" in the Puszta (Great Plains) but these were popularized in their use by Hungarian mounted cavalry much like the better known Cossacks in Ukraine or Russia.
Its a great find if original. Very cool even if not! Its got me wanting one of my own. Next time I am back in Hungary I may look for one. Great piece.