i am advisable?

Internet, for reasons that don't need exploring at this juncture (aka I took a practice licensure test, because I like suffering), I am the proud possessor of a $100 gift card to Penguin Books. Rejoicing! Celebration! But I have to use it all at once, which is...I mean, not that I couldn't spend $100 on books at one go? But being restricted by publisher is kind of a tricky thing.

SO: What books should I own? Don't worry about checking if Penguin has them (although if you know that they do, that's cool!) - if nothing else, it will serve me well to have a list of recommended books to come back to at a later date.