Geez that's a lot of books for one semester! I had to buy like 10 nursing books this semester...but I'll use them this semester, next semester, and fall of next year as well!
I second asking the professor whether the book is necessary or not...and don't necessarily believe what they say.
My history professor that I had both semesters last year said that we needed the textbook plus 3 or 4 other books...and the textbook was the biggest waste of $90 I could imagine since it sat underneath my bed the entire year and was only opened once! The 3 or 4 others were "necessary" in that we were assigned papers to write based on them...but reading them was pointless. I never got lower than an 89 on any of the 5 short papers we had to right, and I read a grand total of 1 of those 5 books and just pulled out quotes that I wrote around for the rest.
So to make a long story short...wait to buy the majority of your books. Other people will have them, the library will have them, and you don't want to waste hundreds of dollars on books you'll never use.