I'm not a practicing AA, so I can't give you exact salary figures, but what I can tell you is that when working in the same hospital, or for the same group, AAs and CRNAs have the same job descriptions and the same salaries. This is assuming they are working in the ACT model, which is the case for 90% of CRNAs. Independent CRNAs DO have the ability to make more if they are working on their own outside of the ACT model. Whether that's a safe practice is another story.
Another thing to consider in deciding which route to go is where you currently are in your schooling. If you are not a nurse currently and have already taken a lot of pre-med type science courses, the time it would take for you to get out there working as an AA would probably be a lot less than it would as a CRNA, so that's something to think about.