Jack,
The RV-12 European avionics kit should come with the GTR 225A.
There are three versions of the GTR 225 with several different price points: GTR 225, 225A, and 225B.
The GTR 225, 225A, and 225B are all certified radios.
The GTR 225 is a 10 Watt radio and has 25kHz spacing.
The GTR 225A is a 10W radio with optional 8.33kHz spacing.
The GTR 225B is a 16W radio with optional 8.33khz spacing.
Van's RV-12 avionics order form just states "GTR 225", but it must be a GTR 225A to have the 8.33kHz spacing. A quick call to Van's would confirm that and would explain the price difference.
This brochure from the Garmin website contains all of the GTR 225 information:
http://www8.garmin.com/aviation/broc...R_225_spec.pdf
Best of luck to you!
-Levi