I paid a thousand yen more than I should have for that product.
I paid a thousand yen more than that product was worth.
この場合、次のような言い方ができますよ。
ーI paid a thousand yen more than I should have for that product.
「その商品に1000円多く払いすぎたよ」
to pay a thousand yen more than I should have で「1000円多く払いすぎる」と表現できます。
ーI paid a thousand yen more than that product was worth.
「その商品の価値より1000円多く払いすぎたよ」
to pay a thousand yen more than ... was worth で実際の価値より1000円多く払いすぎることを表現できます。
ご参考まで！
カナダ 
