Kids become interested in everything they see and want you to buy it for them.
Children want everything they lay eyes on.
この場合、次のような言い方ができますよ。
ーKids become interested in everything they see and want you to buy it for them.
「子供たちは見たもの全てに興味を持ち、買って欲しがる」
everything they see で「見たもの全部」
ーChildren want everything they lay eyes on.
「子供たちは目を留めたもの全てを欲しがる」
to lay eyes on で「〜に目を留める・見つける」
ご参考まで！
カナダ 
