I posted a few days ago that I'm studying for a certification. My study guide of choice is ExamCram2 for 70-315 which I picked up at nerdbooks.com for $20.83 including tax. Since it is local there was no shipping.
A while back Lance pointed out that Nerdbooks.com had moved to the DFW area. I've been to their site but not purchased anything. I normally buy through Amazon because I'll wait until my wife has some things to purchase and we'll order it all together to get free shipping. Nerdbooks is in Richardson which is no short drive in traffic but it was worth it. Not just saving the shipping but the book selection was great! It was self-service - basically buying it over the web right in their store. Pick up the barcode reader at one of the checkout stations to read the book's barcode and then process through their website and purchase like normal. I liked it personally.
You say your not a local? For the same book
Nerdbooks shipping is $5 for the first book and $1.50 for each additional book. Not that bad.