The cost is high when you use the wrong images: You don't get the job, you don't get signed.
DO NOT use overly artistic pictures - they detract from the subject (you). Dramatic lighting with strong shadowing may look great, but is ineffective. What casting agents can’t see, makes them suspicious.
No matter how beautiful they may be, don’t send high fashion shots unless it’s a tear sheet. Casting agents and modeling agencies don’t want to see what a great job photographers or stylists do, they want to see the real you.
You want simple, crisp, images that only show you off.