With some luck we get back our Unity characters. On Order we had some nice suggestions as I think belonging plot sizes.
How about you can buy as many plots as you want to a maximum f.e. 100x100 squares and scaling up the prices of the small plots the more total square you already bought to solve the price difference of a lot cheap small plots to one expensive large plot.
I don't know whether this or resizing all those existing and useless mini plots would be easier to implement but I think it's a good idea.
Same could be done for dragon lairs, there you have to count the cubes to a total of e.g. 100x100x100 (I don't know the proper sizes of a large dragon lair).