Solved

Driver selling price

I want to sell one driver. I see the price auction proposing me - 2.9 mil. That is too little for him i guess.
Can i make the selling price bigger by training for example? Does the price changing over time? If so, how much.
Can it drop as well?

I think a price drop is not possible. But I've never observed a price increase or price drop in the selling price.

Buying, training and selling is not working here?

there would be no financial benefit to buying someone, training them, and then selling them.