You can create AAC's/mp3's from audacity files even without Lame.

Export your audacity file as an Aiff. Then drag the Aiff file into itunes.

Go to your itunes preferences and click on "general" on top. In this pane, hit the button that says "import settings."

The next window will have a pulldown menu that says "import using" and select AAC or mp3 encoder.

After selecting the right choice in the menu, click "ok." Close out of the preferences window.

Back in the itunes library, highlight the song you want to convert. Go up to "advanced" on the menu bar, and highlight "create AAC" or create mp3."

Once the file has been converted, you can delete the original Aiff from your itunes library.

I'm not 100% sure, but I think the resulting mp3 or AAC file will open in itunes automatically, even if you don't open it in the library.