study guides to sell, all practically brand new:
Princeton Review AP US History (06-07) -- $15 SOLD!
Princeton Review AP Statistics (06-07) -- $17
Princeton Review SAT II Math (03-04) -- $15
Princeton Review SAT Math Workout (1996) -- $10
(it's old but it's pretty good if you need to work on the math section of the SAT I)

Kaplan SAT II Chemistry (00-01 ed.) -- $14
(a few marks, but otherwise in great condition)
Kaplan SAT II Biology E/M (2000 ed.) -- $12
Kaplan SAT II Biology (98-99 ed.) -- $10
(bit old, but in good condition, no writing in it)

Collegeboard The Official SAT Study Guide: For the New SAT -- $18
(this book is the best ever, I highly recommend it)

just a note:  study guides don't change from year to year.  compare like a princeton review apush 06-07 with p.r. apush 99-00, it's the exact same thing.