So bits of data are just $10 per GB if you buy 3GB in advance, but $67 per GB if you buy a 300MB plan — and this somehow reflects the reality of a competitive situation, or maps in some reasonable fashion to issues like spectrum usage and bandwidth availability. The goal here is to push 3GB+ users with unlimited plans over to tiered options where they’ll pay at least $40 for that use. If this was truly about keeping the network balanced, AT&T would implement a throttling solution that didn’t choke users by as much as 95% once they exceeded the 3GB threshold. It would also offer data plans that created more reasonable tiers of service. As things stand now, AT&T has a major selling point — if you exceed 300MB a month on the $20 plan, you’ll actually end up paying $40 — $10 more then you’ll pay with that nice, roomy 3GB option.