There's a thread for this : http://www.cosplay.com/showthread.php?t=82941
But be more precise when you ask there and try to cover these :
- what's your budget ?
- what are you going to shoot exactly ? ("cosplay" is vague : do you want to take casual shots of costumes you come across, do photoshoots, shoot masquerades... ?)
- how serious are you about photography ? (are you willing to learn technique in order to do something better, or do you prefer something easy to use ?)
- do you want/need video ?
- are weight and bulk an issue ?