I thought about what it would be like if I were to buy this product and it had scratches/marks on it.
「購入者」は英語で
a purchaser
a buyer
のように言えますが、この日本語を訳すなら、次のように言うのが自然で良いでしょう。
例:
I thought about what it would be like if I were to buy this product and it had scratches/marks on it.
「もし自分がこの商品の購入者で、これに傷が付いていたらどうするだろう、と考えてみた」
ご参考まで!