Yes and now the real discussion about buying and selling girls (later npcs) at the auction houses can start.
I never have said "no" to an invitation to have a drink, a diner, or a discussion about the mechanics of economics in a game I enjoy!!!
We must first define what point of view you are going to use. One thing it´s the point of view of the artist that try to make a perfect piece of slave and sell her with the same broken hearth that an artist have when he sell the sculpture ha have been working the best part of a year and another it´s the point of view of the industrial that buy 2 slaves every single day and sell 2 slaves every day. The dilettante or the professional.
I´m going to stand from a point of view of the professional. Seems a lot more interesting to me. After all, if you are an artist, dirty money is not your drive, your drive it´s pride in crating a masterpiece.
As a professional, you are severely limited. You are limited in days (you must sell slaves fast, because you buy slaves every day and if you don´t sell fast your home will be overboard and you can not dedicate lot of time or fatigue to improve an slave (because you are processing 8-12 slaves to sell at any given point). You need to be fast, efficient and impersonal.
a) Why it is currently preferable, to buy at Watery Eyes, ignore the "value" of the girl/slave, but only look for the modifiers to charisma, beauty and willpower. (Buy girls at Watery and sell them later at Crystal Heights).
I will buy at Crystal Heights mostly, and sell whatever the price seems higher. There are modifiers that count in one market and not in the other. In most cases the modifiers are making buying in Crystal hill more expensive, but they affect to extremely high values, in the 80+ range (for Beauty "just" 70+). You can make a 50 f5 run and find none (or just one) of this super high factors.
But there are a few modifiers that make more expensive buying at Watery Eyes.
ST 40 to 49 (+10 to +19) it´s an extra +200 in Watery Eyes
ST 50 to 59 (+20 to +29) it´s an extra +400 in Watery Eyes
ST 60+ (+30+) It´s an extra +800 in Watery Eyes
And in a Crystal Hill 50 f5 run I get something in this values in 18 cases so roughly 1 in 3 cases.
And there are Age. Age above 30 it´s a -1000 in Crystal hall, and of no value in Watery eyes. And again, I get in a 50-f5 run 18 30+ slaves.
Just for this one alone, I will buy in Crystal hall. In fact, I believe it´s a viable strategy just go to the auctions, buy all the 30+ years old slaves (and the oddball with +30 or close enough ST) and sell it at Watery Eyes. Just playing with the +800//+1000 modifier.
b) Why actively modiffing stats/skill of girls (slaves), except for Willpower (grinding down), Corruption (increasing) and Beauty (surgery), is currently not that profitable.
I believe that´s a matter of world design and world lore.
A Highly skilled (70+), highly inteligent (60+) Doctor have a value of 2.200$. If Scientific or academic, 2000$. A 60+ Beauty, Highly corrupted (70) slave it´s worth 5100. It is what it is and you, as an slaver, don´t argue with the Market. Sure the result it´s that nobody train slaves to be doctors or academics. And oddly, that passes a reality check with flying colors. A Doctor or an Academic slave it´s an oddball. We are talking of a Doctor or an Academic that falls into slavery, not about an slave trained to be a doctor. that can happen, yes, but it would be an slave from a great house that it´s trained for internal use and prestige reasons, but not about a trade practice.
And be aware of surgery increased beauty. It´s only profitable if the slave crosses the 80 threshold
c) Whether it's better to keep a virgin slave an uncorrupted virgin or selling her later as a highly corrupted and totally devoted girl (-15 willpower and 80+ corruption) or in which cases one is preferable over the other.
Always keep her virgin. No questions. If you keep her virgin you get +7500$ (supposed you lower her EP to 5 or less) In the same moment you fuck her, you are throwing those 7500$ to the sewer. Corruption 80+ gives you only 3800$, and it will be a lot of extra work (pleasurable work if you want, but work at all)
d) In which cases it is best to outright sell, recently captured, high willpower female convicts than to grind down their willpower or wait at least a few days before selling.
It´s always worth wait at least 4 days. Even the most worthless slave (less that 1000) in the setting with the most expensive food (20 per ration, 60$ a day if you feed her at 3R, so a total of 240$) and you get an increase of price of 400$, and, at least, 8 influence putting her to work as a maid. And you can go full miserly (shame on you) and feed her with only 1 ration.
But about grinding the willpower, I´m not so sure if they are worth the fuss. it will depend of how big it´s your slaves-for-sale backlog at the moment. But I will let her mostly untouched. They have usually pretty high willpower, and grinding let´s say from 60 to 29 it´s just a 400$ increase, and a lot of clicks and time. If you grind willpower, you grind to the -5 bottom
h) Why girls should usually treid to be sold at Crystal Heights and not Watery Eyes.
Mostly because people are lazy and don´t check both markets. There are by far more cases where you get better prices in Watery Waters.