I was at a local market today and purchased 7 limes for a single dollar.  I squeezed them and put the juice into an ice cube tray for freezing.  For times when I do hot have fresh limes or frozen lime juice, the small bottle of RealLime juice is a perfect standby that takes up little space in the refrigerator.  I'm not thrilled with the preservatives, but understand the convenience outweighs the minor chemicals.