The course textbook is Richard Feynman, "Feynman Lectures on Computation", published by Perseus Publishing. It should be available in the bookstore. Here's the amazon.com link ($32). ISBN number is 0738202967.
If you want to buy it online, you can do that, but it might not get here in time for you to do the reading. According to ecompare.com, the best price is $28.80 at booksamillion.com and $30 at buy.com or powells.com or fatbrain.com.
I have a copy of my own and I have Bill's copy this week (but not this weekend) if you need to borrow. I believe it's also on reserve at the library.