Reddit reviews Supernatural: Bobby Singer's Guide to Hunting

Alright. These two books are based off the series and seem like a cool bit of memorabilia.

(Bobby's guide to hunting)
http://www.amazon.com/gp/aw/d/0062103377/ref=mp_s_a_1_5?qid=1374813077&sr=8-5&pi=AC_SX110_SY190

(John's journal) (very important in the early seasons)
http://www.amazon.com/gp/aw/d/0062073192/ref=mp_s_a_1_14?qid=1374813154&sr=8-14&pi=AC_SX110_SY190

Or there's a nice supernatural themed travel mug that your friend might enjoy. It has a well known quote from the pilot episode on it.
http://www.amazon.com/gp/aw/d/B003KUIX3S/ref=mp_s_a_1_54?qid=1374813272&sr=8-54&pi=AC_SX110_SY190

All of these are around $12 each so you could do a bundle of all of them and still be under budget.

This book just because I love supernatural and anything to do with it.