Some advice on Explorer I pricing

[HFLO]

I am planning my next purchase on either a DD or Explorer I

There are not many (I might be wrong) DD offerings and price seems pretty much 'the same'. But for Explorer I, it seems to be quite a big price range on the various offers found in TRF/VRF.

a quick search shows:
Explorer I Y serial, $2950
Explorer 114270, S serial, 78360 Oyster band, 558B end links, $2600.00
Explorer 114270, U serial, $2,450
Explorer 1, 1016, serial 4.1 milion, matte dial, $6300 (?)


My questions:

without taking into consideration box & paper, and assuming the same 'good' condition (say 85%+) , what are other 'main' price factors?

dial? matter? gilts (gilt dial seems to make a lot of different!)?
model? how many model are there? (114270, 1016?)
year? what are S, Y, Z serial?
band?

thks for sharing. I am 'learning' (very slowly)...