、。
She tried to get a tent at the store, but couldn't find one she wanted.
Literal
She [topic-は] store [at-で] tent [object-を] obtain [tried to-ようとした] [but-が], want [quotative-と] think tent [object-を] find [thing-こと] [subject-が] could-not.
Two grammar patterns anchor this sentence: ~ようとしたが ('tried to X but') uses the volitional + とする for attempted action, and ~ことができなかった ('could not') is the formal potential negative. 手に入れる ('to get one's hands on / obtain') is more emphatic than 買う ('to buy'). 欲しいと思うテント ('a tent she thinks she wants') uses a relative clause with 思う — the embedded thought modifies the noun.