The Paramus, New Jersey-based Letraset division of Esselte Business Systems, which markets the Ready, Set, Go! 3 desktop publishing program for the Apple Macintosh, is offering a trade-in for users of two rival desktop publishing packages, PageMaker and MacPublisher: PageMaker users get the $400 pack for $100, and MacPublisher users get an an upgrade to Ready, Set, Go! 3 for $70 – until March 22; new users also get Ready, Set, Go! 3 for $100 off list until that date.