Update: The super-nice people in my College's administrative offices got with the Bookstore first thing on Monday morning to get this fixed up. It turns out there was another online course that had a similar problem, so they were able to get both problems taken care of. I feel very lucky to have their help with stuff like this!
But I sent my usual email to the students this morning with detailed information about the three required books, and the Bookstore screw-up gave me an excuse to really urge them to look at other sources for the books, since the cheapest options at the Bookstore (rent used for the semester) are usually twice as expensive as the super-cheap used books from Amazon. Of course, since the Bookstore has none of the required books listed right now, I cannot tell just how much they are overcharging this semester...
On the one hand, I am glad for the initiatives my school has pursued to lower book costs (like the rent-used option)... but it bothers me that the Bookstore will only accept one ISBN per book so that there is no easy way to let students know that there are older editions, perfectly acceptable, with different ISBN numbers.
So, I make sure students know that any old edition of the book is GREAT, no problem, and I include links to the old editions at Amazon so they can see the incredibly cheap used books there and/or use the ISBN numbers to do other online shopping at other book vendors. That's information the Bookstore should want from me, too, but their sales model doesn't facilitate students buying used out-of-print editions from other vendors online.
Anyway, I am very pleased that the three books for class can be purchased used from Amazon for under $20 total, and that includes shipping! That is very cool. Three cheers for used books and used booksellers!!!