The plate they want to buy from you is for some reason not worth much but the one they want to sell you is three times its real figure !
I had a good dig into this subject when planning to get the red car and the advice I got fro numerous people was that the resale value of anything but a non dated plate was negligible, with obvious exceptions for a plate that spelled out something significant. So for example, chances of re-selling G1PJB are small, but PJB1 is a different matter.
I still went ahead and wasted £1500.