Here is a comparison of the differences between standard and professional.
The main features that standard version misses, in my opinion are
- motion tracker - this may or may not be useful to you
- wiggler - useful, but you you can do the same stuff without it, it will just take a bit longer
- advanced keying tools - extremely useful if you like to cut out part of a video
- a lot of useful effects - I don't know which effects are not included in the standard version, but I know there are quite a few useful ones.
You can buy the professional version with educational discount for about $350, though the educational version is missing some features that are in the full version! I'm not sure exactly what it's missing, but I think its mainly additional 3rd party effects.
You also might want to consider the Adobe Production Studio Premium bundle if you can get a student discount. The entire bundle is only $200 more than after effects pro alone.