Green Lantern (Corps?) #201
Though this book isn't the 1st appearance of the GLC it is the 1st time the get a self titled book but most importantly it's the 1st appearance of fan favorite Killowog! Recent eBay sales are around $5-$20
Green Lantern #48
Not only is this the 1st chapter in the coast city destruction/Hal as parallax but it's also the 1st appearance of the 4th earth GL Kyle Ryner ( he becomes Ion in #145)
Green lantern Corps #1 (new 52)
A reimagining of the corps and their 1st appearance in the new 52. Recent eBay sales around $5.
Green Lantern: Ganthet's Tale
The Oans were 1st introduced in GL #1 way back in 1960 and is out of most of our price range. However, the 1st appearance of our favorite guardian, Ganthet, is in this book and still very affordable at around $5.
The two major characters mentioned here have been on the silver screen before but seeing as that movie was SO BAD and the spec market being so young maybe, these books will finally get some love when the movie is closer.
I also collect covers by artists. The gawd Jim Lee does covers on issues # 143, 150-155: