If you get the GT RTR all you will need is fuel and 12AA's, it comes with a rechargable glow plug heater.

Personally I have the GT (not the RTR version) and love it. On the other hand, many people have the XXX and love it as well.

BTW I would suggest forgetting about RTR's and do it the right way, get a kit The initial cost will be more, but it's well worth it having everything just as you want it from the start.