Here's the deal:
The "full" Mac Edition is $19.99, comes with the Valkyrie pack and the Mission teleporter, and one full month's of service.
In 2 months, the Mac "Goodies" pack will be released, will be $9.99, and only comes with the Valk pack and Mission Teleporter.
If you do the math, the free month of the current "full" Mac Edition takes the "net" cost down to $5. That's a pretty good deal. ($20 - $15 free month = $5)