For Halloween, I was Mercy Otis Warren, an influential authoress during the Revolutionary War. Naturally, I bought books about women during this time period. This was somewhat influences by several trips to Colonial Williamsburg and the purchase of a period-accurate gown for my costume. Because that's how nerds party, yo.
Anyhoo, I've also made several trip to Paperback, Inc to trade in part of the horde I still have. This means I've brought home several volumes for my collections. And then there is the 6-month thing I signed up for from Persephone Books in the UK - They send me a new book each month. These are gorgeous volumes, of course, lovely selected, thoughtfully published, and creatively bound. Dreamy books, really.
The problem with buying books, really, is time. I have so many good ones and I despair of ever having time to read even a third of them. I suppose, one day, when I am old and retired, I shall do nothing but read all day.