Where can I find good stock of batman poses?

Okay so I'm painting a headboard for my little nephew and I need spiderman and batman stock. i'm going to photoshop them in making it look like they helped me paint it. But I can't seem to find any good ones or full body that kinda of thing. Is there any stock websites you guys know about? Let me know because We just found out that he's having mysterious seizures so I want to get this done (and the headboard) dont fairly quickly. Thank you, Julia