Yup, I've got a house full of books, CDs, and now a growing vinyl collection.
It doesn't help that I am a book sorter for the annual sale of one of our local libraries . . .
My tastes are eclectic. Art, cookbooks, gardening, science fiction (now there's a difficult market to find firsts in---lots of book club editions lying around, tho), modern first editions of books I love, aviation, . . . I like to have a reference library on hand for my various hobbies. I even have a veterinary medicine subsection. Some of it's quite valuable, some of it is ex-library. Sorting books for the library satisfies my 'scavenger-hunt/garage sale' instinct, with the proceeds benefitting the library rather than my overstuffed shelves.
Question on the Modern Library editions (in my 'professional book sorting' hat): I understand all the condition issues, but haven't researched them: what your understanding of value of these neat little books, with dj in excellent conditions. We get quite a few, and I'm never sure whether to mark them up over $3 each or not.