Hi Psyoutlaw,
I've not taken the Psychology Subject GRE exam myself but I know a lot people who have! If you are preparing for Psychology Subject test you can refer to the following resources.
Cracking the GRE Psychology Test, 7th Edition
Price: $18
Kaplan GRE Exam Subject Test: Psychology, Fourth Edition (Kaplan Gre Exam Subject Test)
Price: $19
How to Prepare for the GRE in Psychology (Barron's How to Prepare for the Gre Psychology Graduate Record Examination in Psychology)
Price: $17
Kaplan GRE Psychology
GRE Psychology W/ CD-ROM (Rea) - The Best Test Prep for the GRE with CDROM
Kaplan test prep & admission
Online coaching & test series
Price: $ 499.00
This is pretty much an exhaustive list. Apart from these you can also check out the site subjectgre.com for detailed information on test taking strategies and various information for Psychology Subject GRE test.
Hope this will prove helpful to everyone who lands up on this page in search of valid information.
Thanks :)