Check eBay. I just won an auction for the AB kit for $33 shipped. There was an auction for a used AB kit that has 2 bids and is at $10.50.

 

If your converter box wasn't defective.
eTrailer has an adapter for $19
Trailer Connector Adapter for Land Rover - 7-Way, Round Pin, European Style to 4-Way Flat Tow Ready Wiring 118710

 

If you want to cut off the factory plug and splice some wires. Curt makes a convert kit for $41 MSRP - http://www.curtmfg.com/Search?term=56146

eTrailer has it for $24 Curt Circuit Protected Powered Converter w/ SMT Curt Custom Fit Vehicle Wiring 56146

 

My LR factory tail light converter was not putting out left turn signal, and it was as big as a small child. I cut the factory plug off the old converter, and soldered this in

 

The AB plug and play route is the way I went also. It was super easy to do. I just didn't want to try and cut and splice wires in a small area with my large hands.... just too cumbersome for me. Call it lazy if you want, but the $99 kit was much better for me to use. I just installed it about a month ago and have used it twice so far.

 

For those that need to use an electric brake controller or just don't want to monkey with changing over wiring on a trailer with a flat 7-pin plug, Pollak now offers a 7 pin round (AG)-to-7 pin flat adapter:

Item # 12-724, 7-Way HD Pin Plug to 7-Way RV Blade Socket Harness Adapter On Pollak

Or you can buy each end and wire your own up, like I had to do!

 

At least with the LR kit you know it should work (hopefully) and if not you can reclaim your dosh. The plug and play LR kit also analyses the trailer lights during operation and flags up any defects when indicating (better than the men in blue stopping you to let you know with a ticket). Mine came fitted from LR when bought new as part of the extras deal and have never had any problems in 11 years. To me it's worth the extra few bucks to save all the hassle albeit LR prices are a total ripoff. You may also need to change the indicator module to an HD for the trailer signalling.

 

This will not work with the European 7 pin plug that is on some DIIs from the factory. The European 7 pins plug has wires for Left signal, 12V, Ground, Right Signal, Right tail lights, Brake, Left tail lights)

If you need to run a electronic brake controller, you need to install something like this Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector Tow Ready Wiring 30717

 

Hmm...that's odd. If you follow the factory 7 pin AG (or European, as you refer to it) trailer harness back to the converter box connection, you'll find two unused (unconnected) wires . These seem to work just fine for use with my brake controller...at least on my LR. Maybe mine is special.

 

The factory/ European 7 pin doesn't have all the wires you need to run a North America 7 pin plug with a brake controller. The factory 7 pin has pins for: rear fogs, RH direction, RH tail, brake, LH direction, LH tail and ground.

The North America 7 pin has pins for: power, ground, LH direction, RH direction, tail, brake (controller), reverse.

The European 7 pin is missing: reverse, power, brake controller output.