Maybe I didn't put across the nuance of my point that well. Sancho will be expensive, but there are reasons why Dembele and Coutinho went for extraordinary amounts, because they were fallouts from PSG flexing on Barcelona and had signed a new contract the season before leaving. Pulisic is a supposed starlet and went for £58m. De Jong is definitely a starlet and went for £70m. Sancho going for £160m is frankly absurd, he'd probably break £100m, but not Mbappe levels of price.
Contract lengths are very important, because they act as a reference point for valuation. X amount of wages will add to the valuation, Sancho is good for 30 goals and assists so buying a player to replace that for the 3 years they'll lose will add to the valuation (of course Dortmund won't buy a player for that, they'll develop a player theyve bought for cheap).