Designed for game version 5.10

This mod allows buying and selling of stations, except for defense stations, wharfs, shipyards, trade stations, or any faction's headquarters. These were excluded from purchase because I thought that governments would be extremely reluctant to sell strategic resources.

You can speak to any station manager and get an appraisal for the station, which prints to the logbook.
The appraisal for buying stations is as follows:

• The price of all the station's modules, the price of all drones, the price of all the station's cargo at max valuation, plus the price of the station's build plot. This is the base price.
• Then, every station owned by the faction which produces the same products of the station being appraised are evaluated for their relative prices to get the product which has the highest average relative price within the faction. That relative price is divided by 10 to arrive at a value between -0.1 and +0.1. Negative maximums are set to 0. This becomes the exponent accounting for product scarcity, i.e the scarcest product of a station which has relative price of +45% results in an exponent of 1.045, with a factor of 0 being an exponent of 1.
• If the station being appraised is the last station producing some ware owned by the faction, they automatically assign an exponent of 1.1 regardless of the relative price of the ware. This is to make it more difficult to monopolize every station producing some ware.
• The exponent is applied to base price. Formula ( Price of all modules + price of all drones + price of all cargo + price of build plot) ^ (1 + (relative price of scarcest product / 10 )
  

The appraisal for selling stations is as follows:

• The price of all the station's modules, the price of all drones, the price of all the station's cargo at max valuation, plus the price of the station's build plot. This is the base price.
• Then, the relation of the player with the faction buying the station is checked, and a flat percent bonus is applied for good relations. The bonus scales up to 30%
  

Compatibility with Recycle Ships and Stations: His mod replaces my mod's dialogue for owned stations, but doesn't affect buying AI stations. Thanks to iforgotmysocks for this mod, which helped me figure out the dialogue system and provided a good starting point for my work. His mod does not appraise owned stations' cargo or build plot, so you'll sell for less. His method of transferring ownership doesn't use the library for this purpose, but I haven't tested whether there are bugs with the station accounts in Recycle Ships and Stations.

Other mods which add conversation options to station managers probably also interfere with my mod...I tried to look at Extended Conversation Menu but couldn't figure out how to get that to work.