More extras?

Hi, i have a gig drawing simpsons characters, but i have the limitant that i only can offer 3 extras, but i have many options to offer as extras, but i cant because i only have three, anyone know how can i add more extras to this gig??

http://fiverr.com/aldodel/draw-you-full-body-picture-as-a-simpsons-character


Thanks for your comments