I saw the prices for Allegro Common Lisp and Lispworks. 600 and 2000 bucks, respectively, per user.

IMHO, so much nicer than emacs + SLIME. but really I never liked emacs. (no flame intended).

I get a

"java.lang.NullPointerException"

whenever I try to load the REPL. Any suggestions?

I got mine to work on the first install. Do you have the latest JRE installed?

Yes, I do. Does it have something to do with installing a LISP implementation?

Hmmm dunno much about that friend...