Is the 50 buffalo gold coin valuble?

If it is the genuine mint product, yes, it is worth the value of gold in them. It is worth at least $1,422.50 at the time of writing because that is the value of the 1 troy ounce of gold, however, American Buffalo coins (which is what I'm assuming you are referring to as it has a face value of $50) trade at a higher premium than spot price, however, these premiums change based on collector demand and what year and condition so I can't accurately tell you for sure what the premium is.

However, beware of TV sellers selling "non-monetary" copy coins, these coins will say "COPY" somewhere on them, these coins are essentially worthless, contain a -tiny- amount of gold plating (as in, it would cost more money to remove the gold plating than the gold is worth), have absolutely no collector demand and make absolutely terrible investments.