If I had $100 to spend with the collection of books posted, I'd consider maximizing the bang for the buck and going heavy with PDFs. Specifically, Green Ronin's Advanced Bestiary and Advanced Player's Manual are absolutely awesome and packed with material at a good price. E.N. Publishing has great stuff for a good price. You can never go wrong with Monte Cook and Malhavoc Press as well. Dungeon subscriptions are good, and honestly, as a DM, I still get tons of great ideas from Dragon each and every month. After you buy Advanced Bestiary (best monster book available, IMHO), if you want even more monsters, check out the product line of Silverthorne Games. I wouldn't spend anything on a WotC book, not that they aren't fantastic, but with only $100.00, they are going to eat up your funds fast!
Charles Plemons