It's time to be a big boy and install from source. Try this:
1) Download the MySQL-python-1.X.X.tar.gz file(by default will go to your Downloads directory)
2) Open a Terminal window and cd to the Downloads directory.
3) Unzip the file you downloaded:
~/Downloads$ tar xfvz MySQL-python-1.X.X.tar.gz
That will create a directory inside your Downloads directory called MySQL-python
4) cd into the newly created directory.
5) Typically, you just open the file called README or INSTALL and follow the instructions--but generally to install a python module all you do is:
$ sudo python setup.py install
If you care to look, there should be a file called setup.py inside your newly created MySQL-python directory, and you are invoking that program to install the module.
Also note that this:
export PATH=$PATH:/usr/local/mysql/bin
is not permanent if you did that on the command line. You need to put that line in a file called .bashrc in your home directory (~/ or equivalently /Users/YOUR_USER_NAME). To see if .bashrc already exists(it's a hidden file), issue the command:
$ ls -al
and look for .bashrc. If .bashrc doesn't exist, then create it.