Is it possible to purchase audio lectures on CD?

Yes!

Thanks for contacting us about purchasing our lecture content on CDs or DVDs. We now have a partnership with CBD and lecture content may be purchased through them at our bookstore page here: http://biblicaltraining.christianbook.com/Christian/Books/cms_content?page=3048087&sp=117063&event=HPR2, or by going to the BT home page, click on the Christianbooks.com link, then in the middle of the page, click on Biblicaltraining.org: Class lectures on MP3 CD.