what its the value of a 1977 $1.00 bill that has the back of the bill double printed on the front?

Answer 1

You need to take it to a currency dealer. Most error notes do not have a fixed price list like all the other notes. They are a specialty item, like error coins. Anyway it needs to be seen. If your local dealer of coins has few notes, find another that know paper money. See if there is a local coin club, it's members would be glad to help.

Answer 2

Look it up on ebay, they always have something posted and if you want to sell it now you have a better judge of how much people will spend on it. Serious collectors keep an eye on ebay b/c you never know when something will pop up.