nǐ / jū rán / huā / nà me / duō / qián / mǎi / zhè ge / pò / dōng xi / zhēn shì / nǎo zi jìn shuǐ / le

你居然花那么多钱买这个破东西，真是脑子进水了。

You actually spent so much money on this junk—you've really lost your mind!