The primary source for all audio lectures by Dr. Greg Bahnsen is Covenant Media Foundation.
CMF has done a great service for the Church of Christ, as of this post edit, most if not all Dr. Bahnsen lectures/sermons/teaching are available to listen to/download for FREE! I will link to the Apologetics section below, but use the pull down menu to select other important areas of teaching such as Philosophy, Ethics, and more. Click on the down arrow to expand the results of the desired series.
COVENANT MEDIA FOUNDATION FREE BAHNSEN MP3 DOWNLOADS
Other Sources:
Worldviews in Collision: At War with the World I – Part: 1 of 2: DOWNLOAD
Worldviews in Collision: At War with the World II – Part: 2 of 2: DOWNLOAD
Van Tilian Apologetics, I – Part: 1 of 4: DOWNLOAD
Van Tilian Apologetics, II – Part: 2 of 4: DOWNLOAD
Presuppositionalism 101 
Thank you for your ministry. As an open air evangelist I needed resources that would provide me the material I need to answer questions of the so-called “intellectual person” . You have provided a treasure of resources that I look forward to diving into. Thank you again. Grace and Peace, Jon
These are great! If I want to use a small clip from this on a podcast is there any copyright attribution I need to attach?
Probably be best to contact Westminster Theological Seminary, send an email asking for permission to: communications@wts.edu
I sure will, thank you so much!