You can do a Google search for:
site:craigslist.org "iphone 4"
to get a sampling of classified ads for then, going rates seem to be $75 to $190 depending on condition, as iPhone 6s deliver you can expect the value to further degrade.
about a 100$ depending how many gb it has and condition
considering the iphone 6 is coming out the 19th and only cost 199$ your probably not getting more out of it
About $80;
http://swappa.com/buy/apple-iphone-4-ver...
Depends on condition, probably $80, 4 is quite old now, thats almost 4 years ago.
It depends on the Network, Capacity, and Color
