Turn it around how many times you want.
Try to take the conversation outside of the subject discussed.
Facts are still facts...
This game is about BB-managing, not about BB-agent, or BB-eBay.
Having hundreds of percentage difference between buying and selling the basically same player will never happen in any real-world league.
How to do it?
Very simple.
Define a formula that combines all values as an init values, and then let the market do its course.
This course will be limit by 10-20 percent difference on each transaction of the same player.
In case that player had been trained, or changed his skill in any other way, the calculation will take that as a factor as well.
When wanting to solve something it can be done.
Surely this simple thing.
Stop going around the bush.
What you are doing just proves how wrong the current system is.
Luckily, the BBs does not think that all my suggestions are "silly", and they created the "Ask the BB" forum, probably due to suggestions like mine of having "A forum, an hour a month, with the BBs".
From there, we (me and others) can hope that those things and others who turn this game away from its purpose (BB-managing), will be fixed.