Boy quiet I don't know how I missed this thread! Oh yeah, I was in Phoenix
Performance and reliability are paramount. I don't think going with any lowest priced option is a good idea, not on a hosting project of this scale. You should be in the .15-.25/gig range, depending largely on how large your swings in bandwidth are. The reason for this, whatever provider you choose has to have available at any one time all of the bandwidth you could ever possibly use at a peak time... open and ready for you to use.
No doubt there are a ton of companies that would suck your dick to get this kind of business. As I am sure you are aware, being able to keep your business isn't something that all of them would be able to do.
If you decide that you are in the market or just want someone to speak to about it, don't hesitate to contact me. Whether or not I ever have your business I'm happy to help in any way possible.
Cheers,
Brad Mitchell