Buying a share before getting one's PPL is not likely to be a good idea because the group's insurance may not cover the plane for ab initio training. Also, the plane must be maintained to a different regime if used for training towards the initial award of a license or a rating, and this makes it more expensive to keep. Finally, it is wise, if possible, to train in the same plane which you want to fly later on...
If however you have a clear idea of what you want to do post-PPL (e.g. going places i.e. touring) then buying a plane outright is a good strategy. Practically everybody will tell you that you are crazy, of course
But it saves an awful lot of hassle, conversion training, etc.
Training in the USA is a sausage factory only if you go to the big schools.