For if the willingness is there, the gift is acceptable according to what one has, not according to what one does not have. (NIV)
For if the [eager] readiness to give is there, then it is acceptable and welcomed in proportion to what a person has, not according to what he does not have. (AMP)
For if there be first a willing mind, it is accepted according to that a man hath, and not according to that he hath not. (KJV)