You have two options here. Expressions or a 3rd Party app like Newton. For expression help the best source is Dan Ebberts site. http://www.motionscript.com
Newton may be expensive but it does things that you can't do in AE any other way and I find it well worth the price.
Is $250 for a plug-in expensive? Trapcode Particular is $400...
Seems very fair.
I am getting it.