rollcage prices??

Well it's finally time to get a rollcage. I've been told that my best bet is ordering a prefabbed roll cage & then paying for someone to weld it in. I haven't had a chance to look into this yet really. So how much do you guys think I'll have to pay for everything? I'm looking for a 6 point rollcage. I'd like to go chromoly if it's not too much more. Also, if anyone has any chassis/welding shops that they recommend in the L.A. area, please let me know. Thanks.