Butler only takes 3-12 (the number differs depending on who I talk to) transfer students a year. You have to get in at least the 75th percentile for every section of the PCAT, and your GPA has to be quite high. That's all they consider.
Purdue's requirements are much easier - approximately 1/3 Indiana students (meaning students who go to universities in Indiana besides Purdue, like IU, Ball State, etc) get into Purdue. I think in state the GPA requirement is 3.0, and you do not have to take the PCAT. They put quite a bit more emphasis on leadership, letters of recommendation, pharmacy experience, etc. than Butler. Purdue is also cheaper and it's huge. They do look down on retaking classes and I believe you can only get 2 Cs in your prereqs, maximum - so do not slack off freshman year, it will hurt you!
I went to Purdue University for undergraduate (psychobiology) and will be attending Butler this fall as a prepharmacy transfer student. Purdue has a great pharmacy program, but personally I don't like Lafayette and prefer a small-school and the general atmosphere of Butler. I think Butler will be a better fit for me.
I recommend volunteering in a hospital or clinic when you turn 18, and try ot get a job as a pharmacy technician. I don't know if pharmacists will let you shadow - my boss doesn't let people because of HIPAA regulations.
When you get to school, get to know at least one science/math professor really well, because you will need them to write you a letter of recommendation later. Your classes at IU will have 100s of kids, so go to office hours! I never took this advice but I wish I had - you will never get to know the professors if you don't go to office hours or do research or something.
If you have any questions, feel free to ask/PM me!