http://www.theartistschoice.com/perez.htm
Spencer has about 15-20 9x12 character sketches of various heroes. There are some really good ones over there, so I don't want you guys to miss out. The Joker, Powergirl, Thor, and Ironman are really nice. They rage from $125-$150
He has also has
Captain America
Hulk
Silver Surfer
Scarlet Witch
Firestorm
Martian Manhunter
Wonder Girl
Hawkeye
Beast
Some others that I am forgetting.
Let me know if you guys get any.