I didn't compile this wxMaxima.app myself, but I believe it's OK. So
perhaps there really is a problem specific to your machine...
In your place I would delete the wxMaxima preferences located in
~/Library/Preferences
(~ stands for your home directory)
and try to launch it again.
If wxMaxima still looks in /usr/local/bin, then perhaps a dirty
solution is to make a copy of wxMaxima.app there so it will find the
files.
Again, I don't know exactly what is the problem.. I'm guessing here.
Report if there is any progress..
Regards,
Ziga