I found a few things on sale over the weekend, so this is what I've ordered. My plan is to break the boxes open, and give each girl one book.
Cherry Ames books 9-12 - $12.58
http://www.amazon.com/Cherry-Nursing...ds=cherry+ames
(I see that the price is $19 higher today!)
*****
Nancy Drew books 1-5 - $17.38 + $3.99
http://www.amazon.com/Nancy-Drew-Sta...ew+starter+set
*****
Cherry Ames, books 1-4 - $19.49 + $3.99
http://www.amazon.com/Cherry-Boxed-B...ames+boxed+set
So that comes to 13 books for $57.43, or $4.42 each.