I'm learning Kiddushin this year and while I haven't yet gotten to the Sugya which delves deeply into the issue of how to derive kiddushei kesef from the gzera shava "Kicha Kicha" I know that kiddushei kesef is learned out from Avraham purchasing Ma'arat HaMachpela from Efron (Kiddushin 2a). From the fact we know that land can be bought with kesef we use a rule of parsimony to assume that the land Avraham actually was makne the me'ara with kesef.
Now as I was learning the parsha this morning and came to the point where Eliezer is mikadesh Rivka as a shaliach for Yitzchak it dawned upon me that this would have been a perfect source to learn out Kiddushei kesef.
וַיְהִ֗י כַּאֲשֶׁ֨ר כִּלּ֤וּ הַגְּמַלִּים֙ לִשְׁתּ֔וֹת וַיִּקַּ֤ח הָאִישׁ֙ נֶ֣זֶם זָהָ֔ב בֶּ֖קַע מִשְׁקָל֑וֹ וּשְׁנֵ֤י צְמִידִים֙ עַל־יָדֶ֔יהָ עֲשָׂרָ֥ה זָהָ֖ב מִשְׁקָלָֽם׃
I am aware it is debated which one of Eliezer's two gifts actually constituted the Kiddushin. However I'm surprised this pasuk isn't even brought up in the Gemara.