There was an awkward moment when I was asked to guess the price of something and thought it was super cheap when actually turned out it was really expensive.
私こそ、「これいくらだったと思う?」「私何歳と思う」というような質問が苦手です。
気まずい空気が流れた = there was an awkward moment; there was an uncomfortable moment/silence; there was an embarrassing moment/silence
クソ低い価格 = dirt cheap
I was asked to guess the price of something = 「これいくらだと思う?」と聞かれた