if you must you must have the most recent version, then buy whatever new at full price. but if you're just learning, most likely a book for a less recent version will do you just fine. many are available used on Amazon for under $15, and sometimes you see ridiculous prices, like Secrets of the Pros for $1.75 (true). though sometimes you end up with broken CDs and have to deal with jumping through hoops to get a return (anybody know where I can download the files for Sybex/Alias' Learning Maya 5 Character Rigging and Animation? ouch. rather get the files than cost the company a sale and have them toss an otherwise okay book).
plus you get the benefit of reading other users' reviews, which can help you avoid hyped books that nobody actually seemed to like, and maybe find some winners that aren't distributed so widely.
(oops, meant this as a relpy to the geez maya books are expensive thread)