That scripture doesn't say what you said. Where does it say it is a free gift?
The saved are bought and the bought ones are given the gift.
Gifts are, by definition, free. The person receiving the gift doesn't have to pay for it or work for it in any way. They only have to accept it.
Why do you reject plain scripture?
but just in case you needed it spelled out for you, GT, here is Paul, calling it the free gift:
Therefore, just as through one man sin entered the world, and death through sin, and thus death spread to all men, because all sinned—(For until the law sin was in the world, but sin is not imputed when there is no law.Nevertheless death reigned from Adam to Moses, even over those who had not sinned according to the likeness of the transgression of Adam, who is a type of Him who was to come.But the free gift is not like the offense. For if by the one man’s offense many died, much more the grace of God and the gift by the grace of the one Man, Jesus Christ, abounded to many.And the gift is not like that which came through the one who sinned. For the judgment which came from one offense resulted in condemnation, but the free gift which came from many offenses resulted in justification.For if by the one man’s offense death reigned through the one, much more those who receive abundance of grace and of the gift of righteousness will reign in life through the One, Jesus Christ.)Therefore, as through one man’s offense judgment came to all men, resulting in condemnation, even so through one Man’s righteous act the free gift came to all men, resulting in justification of life.For as by one man’s disobedience many were made sinners, so also by one Man’s obedience many will be made righteous.Moreover the law entered that the offense might abound. But where sin abounded, grace abounded much more,so that as sin reigned in death, even so grace might reign through righteousness to eternal life through Jesus Christ our Lord. - Romans 5:12-21
http://www.biblegateway.com/passage/?search=Romans5:12-21&version=NKJV
Read it. Don't just gloss over it.