You might consider ScaleEngine, I don't think I'd classify them as "cheap", but they're cheaper than AWS and Rackspace and you *can* talk to a real person.
In my experience, however, very high bandwidth delivery of relatively large files works best if you roll your own. That is, CDNs are great, but I've yet to find one that can come even close to matching the prices you can get by going colo and buying bandwidth directly. Obviously, for very small files (image sprites, css, js, etc), as big CDN like Limelight, Akamai, Highwinds, Level3, etc, will give you a TON of locations and truly amazing delivery.
When delivering larger files, however, I frankly don't see the need for city-level POPs. Rather, 1-2 POPs in each geographic region suffice (the extra connection establishment time doesn't matter if you're transferring several 10s to 100s of MB). On the other hand, it takes a fair amount of outbound bandwidth before this makes sense.
Just my 2 cents.