Tā zài jiùshūdiàn zhǎodào le nà běn juébǎn shū, rúhuò-zhìbǎo.
He found that out-of-print book at the secondhand store and was thrilled as if he'd found a treasure.
Tips
history
From the Song-dynasty letter 《与胡邦衡书》 by 李光: 忽蜀僧行密至,袖出寂照庵三字,如获至宝, 'Suddenly the Sichuan monk Xingmi arrived, drew three characters from his sleeve, and I treasured them as if they were jewels.'
grammar
Pattern: subject + 如获至宝, or as a comparison after 一样/似的. Often paired with verbs of obtaining (得到, 找到, 收到) or treasuring (珍藏, 收好).