I am very interested in purchasing your (something) and wondering if you would be willing to part with it.

這是照你所寫的所翻, 但你自己的文意有點怪, 如果人家已經要賣了, 幹麻還要問人家肯不肯割愛. 如果人家根本就沒說要賣, 那我覺得不該一開始就說你要買人家的東西 (有點有錢就了不起的感覺).