Hmmm well for $40 or so I hate to say there is not a whole lot out there but you may be able to swing a Nismo keychain or something somewhere for that price which would be cool. You could prolly find a Nissan keychain somewhere for cheaper that would be nice.
Yes the SE comes with a SR20DE which is a nice motor. There isn't a whole lot out there for the SE like if you wanted to go forced induction but you can find all the bolt-ons for it and suspension parts from any B15 so there is no shortage of nice suspension setups.
And the Audis are very nice cars also. I have been wanting to get my paws on an S4 for a while now