Not worth it. My BS degree before med school was biochem; you won't use an organic text, you'll use a biochem textbook and maybe, MAYBE, look at notes from organic once or twice. For the MCAT, you don't need to know in depth mechanisms, not to the extent that you need to go to a textbook anyway. If you took good notes throughout organic, that would be more than enough for the test.
get some money for your book while you can. And as for that personal library, I'm about to graduate med school and I as I type this, I'm staring at a general chemistry book, a genetics book and a biochem book that probably would have fetched me $200 if I would have had the sense to sell them a couple years ago but I too wanted that proverbial "library". Take the money, the library's not worth it.
My $0.02