Examkrackers Price Difference from Official Site and Amazon, B+N, etc

Getting ready to order the complete Examkrackers Study set, but I've been browsing, and it costs $275 on their site but less than $200 on other (reputable) sites like Barnes and Noble and Amazon. I just don't want to order it and not get everything that is included on the Examkrackers site. Anyone have any experience ordering this? Is there any reason not to take the cheaper option?

Thanks in advance!