Plate values are sentimental mostly. As people say before the valuation means nothing unless you have someone willing to purchase it off you.
I have one from my first Golf Gti which has been with me a few years and now quite happy to ofload if anyone wants to buy for £500? or i will give it to a family member in a year once the rentention runs out.
The registration is XIA 237 - PM me if anyone wants it.