Can't speak towards commercial listings......but if I were approached for a such request I would do it for a small fee or something similar to that. Why not offer a fee for the information?
I won't list anything I can't sell as my reputation is on the line. That means not taking overpriced junk and an unrealistic seller.
I have a huge network of direct buyers so if it is priced right it will not expire. Sometimes a seller will have a property not listed but off market. I wouldn't share that information openly but to my buyers.
If you want to get direct with sellers you need to do mailers, internet, and a whole host of other strategies to get in front of them. An agent can pull some expired MLS listings for you for a database but something has to be in it for them as they are not a charity.
Most commercial listings aren't on the MLS. Many commercial brokers aren't even Realtors, a member of the National Association of Realtors, which is an option for a licensee.
Saying expired listings means that broker no longer has an agreement to sell. It also means they can't show it or step foot on a property with a buyer in an agency capacity. So, they won't be giving you a list of anything. If you're interested in say, a warehouse, they will contact the owner and renew an agreement and then show it. :)