Out of all the auditions sites I would say StarNow is by far the best. They actually check to make sure the jobs are real & they have way more than any of the others I'm a member of. I know they have been around for over 10 years and I follow them on Twitter where they post urgent paid jobs which is great for me as I'm super busy with University and only want paid extra work.
My mate got an agent from StarNow & their customer service is pretty quick (especially if you tweet)
A very useful site for auditions & jobs and better priced than many of the others.