You will probably need a conventional trainer, and then a low-wing sport plane and get proficient with both before flying the big Extra. Those big planes are fairly expensive, and if you crash it, your wallet will hate you, especially if you are on a tight budget like it sounds like you are.

That big gas extra is a very advanced plane and I would recommend flying for one or two seasons before trying your hand at the extra, maybe get somebody to buddy box you with it your first time if you aren't sure if you can handle it or not.