It's not about paying what they're worth. Pakistan needs Western "aid" and badly needs foreign currency to circulate in their system . Send it in the form of an overpayment for 200 MBTs.2.5 mil for 30 year old tanks with no upgrades is too much, even 1 mil is a lot for those tanks.
"We'll pay $1.5 million for each tank, with spare parts and ammunition. For every tank you sell us, it comes with an additional $1.5 million USD aid bonus".
That's just good business. Maximize the amount you get out of the Pakistani's in the deal, while sending them fare compensation, along with financial help in return.
For the economies I'm talking about (Britain, France, Canada, Italy) $200 million each is peanuts in order to equip two Ukrainian tank brigades with an MBT that they already know how to use and service and already have logistics lines established to support .
It's not about simply overpaying for the tanks. It's about maximizing the efficiency of the purchase, while ensuring Pakistan feels adequately compensated (they need cash) so that they'll continue to sell you weapons for Ukraine in the future.