Ever heard of Mobiltape?
It's a company that specializes in recording presentations and seminars at professional conventions around the country. Although intended primarily for people who've attended these conferences and want to revisit certain presentations, these recordings are also sought after by those who couldn't attend live.
In any case, Mobiltape also sells these recordings to anyone that wants them, and - as the old prospectors used to say, "Thar's gold in them thar hills!"
For example, the annual International Builders Show produced by the National Association of Homebuilders provides all kinds of valuable information to its attendees, who spend thousands of dollars to attend each year. But YOU can help yourself to the content for a lot less.
Individual sessions recorded on CD are priced as low as $15 each. Topics range from Marketing to the 50+ homebuyer to Color and design trends to Tips for the first-time developer to Alternatives to traditional financing, etc.
The search function at Mobiltape.com is robust. You can search by organization, speaker, topic, etc. For instance, I typed in "Real Estate" under topic and among the 9 presentations with real estate in the title was this one: