As you are aware, SQL Server Audit can only be done on Enterprise and Data center editions of SQL Server 2008 R2.
However, the article mentioned above briefly mentions SQL Server Trace (SQL Profiler is the GUI). SQL Server Trace can be used to trace all batches that run on your server. This will give you a good degree of auditing, although not at the level that the SQL Server Audit provides. There have been articles on this:
And others as well. People used SQL Server Trace and Profiler for years before SQL Server Audit and doubtless many who cannot afford the more expensive versions of SQL Server will continue to do so.
Happy New Year ... Wish u good luck...