Well the Creative Suite is basically all of Adobe’s latest programs in one package at a lower cost. Id suggest you just buy the CS package rather than just Flash. You’ll end up needing Photoshop,Illustrator and all of those goodies eventually, it’s worth the cost.
If you’re a student, you should be able to buy it at a discounted student price (ask your school about it). In fact you can even get some software entirely free… I’m in some ComSci classes at my community college and was able to get MS Windows XP Pro as a free download, believe it or not. I dont think Adobe has an offer like MS does though of course…