A Small Fraction
Eric Kim, in a classic:
I would argue that buying even 5 great street photography books will do more for your photography than any lens out there would. And assuming that each photo-book was $50, that would cost $250. That is a small fraction of any lens that you could purchase out there.
Good reminder this weekend, when you have some time for reading. And for the holiday season, when those Amazon gift cards come rolling in.