The sandbox does not charge for API units.

Users just need access to a Google Account username and password. Best practices for the sandbox can be found here.Google has extended the length of time that theyll support both this version and the previous version, v13. The company has done so because the changes between the two versions are so significant. Google intends to retire v13 early next year, but will announce exact dates in the coming months. In anticipation of retiring v13, we strongly encourage you to begin development for v2009 as soon as possible, Fitzpatrick tells developers. Were still working on making v2009 better, so this is also a great opportunity to provide us your early feedback.Over the next several months, Google will be releasing more functionality for v2009, such as asynchronous calls, partial failure acceptance, keyword optimization tools, and reporting.