Besides original DavidCo. products, there is actually no "GTD approved" available commercial planner.
Therefore, they must be addapted according to the needs and likes of each individual user.
Examples of planners can be found at:
FranklinCovey (www.franklincovey.com)
DayRunner (www.dayrunner.com) - Dayrunner does have GTD based planners. Use their search bar and type in GTD.
Daytimer (www.daytimer.com)
You can also make your own planner using an A4 or A5 sized ring binder,
download forms from DIY Planner then print the pages you need.