You can create a simple shapefile for the land geometry. Then in the corresponding attribute table, you add a field named 'Price' for example. Then, use the field for generating your map!
I agree with the suggestions, if you have for example some cadastral map in any vector format you can transform or import it into a polygon shapefile and then add the price information. If its in raster format you can vectorize or digitise it into a shapefile although is more time consuming. I can suggest also free software such as QGIS. regards