I priced US cellular 3G/LTE data access recently. I was looking for something like $10/GB with 12 month expiration, I could then spend something like $60 every 2-4 months.
I didn't find anything like this. Disregarding device cost, most vendors came in at $50/month for 2GB . That included DataJack, T-Mobile and AT&T iPhone tethering.
Virgin Mobile (Sprint reseller subsidiary) seemed to be $35 a month, so it had a clear price advantage.
The best data access was an iPad at $30/month (no contract), but I assume a good part of the LTE iPad's price premium is an up-front payment to the carriers. So this pricing is probably equivalent to the Virgin Mobile pricing. A March 2012 article claimed Verizon allowed LTE iPad tethering, but that seems quite unlike them. I haven't found any discussions of this; I assume it's false.
More recently AT&T and Verizon have "coincidentally" created very similar shared data plans that are effective price increases for most customers -- their "peculiar" coordination makes it unlikely that either will compete on price (or anything).
The bottom line was a significant price advantage with the Virgin/Sprint MiFi, but after reviewing the market no solution appealed. My impressions are:
- The MiFi market is going away. Carriers don't like them, and they're too geeky for most consumers. The US market is being driven to device-specific LTE access.
- Tethering is going away. Carriers don't like it; even T-Mobile doesn't seem serious.
- AT&T and Verizon have carved up a nice duopoly in the US. They may weather the end of SMS better than most of us would hope. Sooner or later, we're going to have to sign on to their shared data plans.
 Of course they rarely price things so clearly; I just looked at what would provide me with 2GB over 30 days. This is contract-free pricing. There are often hidden fees and caps tacked on to mobile charges; these corporations have mastered the profitable art of concealed pricing.
 The most anticipated product in recent Apple history. I suspect it will be $300 without a Retina display.
Update: Virgin Mobile USA is a Sprint subsidiary, no relation to Virgin any more.
Update 7/22/12: I managed to overwrite this post with an older version. Oops. Here's roughly what I removed:
- Enon tells me in comments that the Verizon 3G/LTE iPad provides hotspot service at no extra fee - at least under his contract. The current contract may be different, but this is worth looking into. This would be a significant advantage over the AT&T 3G/LTE iPad! The monthly data fee for an iPad is $30 (cheaper than Virgin Mobile), but I suspect the purchase price of an iPad includes a carrier payment. So the real cost is probably about $35/month and thus comparable to a mifi. Even so, this is/was probably the best hotspot deal on the US market.
- Sprint iPhone has no tethering advantage, it requires a separate payment plan.
- See also: Benedict Evans • iPhone pricing and US market share. Interesting examples of how subsidy agreements in different markets changes iOS value.
Update 7/22/12b: Things aren't quite as bleak as I'd though. Walmart and others are trying to spoil VerizATT's party.