Do you want to become a climber, or do you just want to climb Rainer? I got in to climbing(7 years ago, shit I'm getting old) by taking a class with some friends. The class emphasized glacier climbing with the graduation being a summit attempt of the big R. We (me and my buddies) completed the class and all summited Rainer. After the climb none of them ever climbed again. I however, was hooked. The rest is history. So- if you just want to knock off Rainer, I would recomend RMI (save you the time and $ of buying all the gear). If you want to get into climbing- start hooking up with people- meet people on this sight- climb something every weekend- Rainer isn't really that great of a climb.