I have both of them, bought them years ago when they first came out from Mach One Inc. who I think is the company who published them first. They are definetly worth the money just for the photography alone, but the text is a good read as well. The $400 version of Sled Driver is if I remember right an "enhanced" version printed on heavier paperstock, and it's also a bigger book in size giving the pictures a lot more depth. I almost shelled out the 400 bucks last year at the CLE airshow, but a quick reality check of my at the time CFI wages kept me from picking it up. Now that I'm making the big bucks as a new hire ERJ FO I might buy the "enhanced" version, if that happens I'll gladly sell my old one to someone who can appreciate it.