I've got to come in from the Sun, once in a while, and it drizzled for two hours one day!

FWIW - A correct model 1898 sight is relatively hard to find loose. To a collector a model 1898 rifle sight may be worth about twice the value of a model 1902 rifle sight, in any of its variations.

(With carbine sights, the model 1902 carbine sight is likely rarer than all other carbine models, but, that does not translate into dollars or demand).

On a rifle, when the originality is questionable, a model 1898 rifle sight probably doesn't add much value. (IMHO - $0 to $30).

Other KCA members with access to relevant sources may have better insights.