These 1 peso coins are made of copper-nickel, so they are worth very little when in circulated condition, much less than $1 US dollar per coin.
Coins that are in fully, absolutely uncirculated condition are sought by collectors. Some collectors will usually pay a few US dollars for such a specimen.
Now there is also a subtle variation that adds value to this coin. This is the kind of stuff that gets collector juices flowing.
Our secondary image shows the date from a 1978 peso. Do you see how the top of the 8 is open? This is called an 'open 8' variety. Here are catalog values for fully uncirculated examples of open 8 coins:
1978 open 8: $15 catalog value when fully uncirculated
1980 open 8: $10
1981 open 8: $7
1982 open 8: $10
Even with an open 8, average circulated coins are worth only $1 or $2.