Xero has various different pricing options for your Xero file, depending on how you intend to use it.
The prices below are monthly and exclude GST.
Plans only available via a Xero Partner (Beany)
Non-GST cashbook - basic cashbook for non-GST registered entities and doesn't allow any invoicing - $12 plus GST
GST cashbook - basic cashbook with GST functionality and does not allow any invoicing - $21 plus GST
Starter - allows up to 20 invoices per month and an unlimited number of bank transactions - $29.00 plus GST
Standard - allows an unlimited number of transactions and invoices - $62 plus GST
Premium - includes the multi-currency functionality - $78 plus GST
Payroll add-on - for $10 plus GST per month, the first employee is free, and you can add additional employees for $1 plus GST per employee
Here is a link to Xero's full pricing details.