I'm a land use Civil in SD and 95% of our work is City of SD. In my experience lots are rarely worth what sellers think they are either because site prep costs are extremely high, or because they have lots of costs and risk to get to a buildable product. All the 'good' dirt is gone, so everything left is more and more expensive to build on.
If you negotiate a good deal with that in mind hopefully you can be successful at your endeavor.