Just sticking my nose in ... does 3 score mean £60? (Sorry to be old-fart-ish

) Only I recently bought a 9 inch (23cm) one of those 8473's in Ruby for £38. Mind you, the dealer didn't know it was WF and told me it would have been more if she had

(I told her what it was AFTER I bought it

)
Emmi or another WF person will no doubt be able to tell you better than I things like which sizes and colours are more valuable. You can search the catalogues and see which were made for longer, and thereby get an idea of rarity, but on occasion you may find there are anomalies of which only WF aficionados are aware
However, as a general rule, the colours which were made for longest are likely to be more easily found, but you do need to search every catalogue, to find out if certain colours were only made in certain years, and if some sizes - like my 9 inch - were discontinued! It does get complicated, and personally speaking, I get easily confused

(and therefore prefer to try to pick other people's brains

)