I am a consulting forester. I'll tell you what I know about locust. It is useful to farmers as fence posts, but there is no industrial-level market for the species that I have found. The people who take it are usually the ones who want to use it, rather than a sawmill buying it and marketing it from there. So unless you can find a farm nearby who has a use for it, you may find it hard to unload. It has limited use for wildlife. You often find other species growing among what looks like a pure stand of locust, including cherry and black walnut. If so, you could do management activities that would encourage these other species to gradually replace the locust. When hop-farms were being put in all over the place (only a few years ago), I heard stories of hop farmers paying $100 apiece for locust of very specific lengths and diameters. I never got to verify this because the hype was over before it started and there are not many hop farms in my immediate area.
Good luck if you should buy the property. You are best NOT factoring any potential income from the timber when figuring up your price.
Peter Collin
Portageville, NY