The Samsung Galaxy Nexus--or Nexus Prime, if you believe--isn't officially available in the U.S., but at least a few places online say they can send you an unlocked version of the phone this week.
Expansys USA first got a batch of the unlocked Google phones running Android 4.0 Ice Cream Sandwich last week, and they sold out in 16 hours. U.K.-based Expansys seemed to be the only site offering the unlocked Galaxy Nexus direct to U.S. consumers. The Galaxy Nexus hasin the U.K. Expansys has continued to take orders and says it will be restocking and shipping out more phones this week.
Expansys is selling the unlocked version--compatible with AT&T and T-Mobile--for $750 with free shipping and the expectation that it will ship within three days.
Meanwhile, British retailer Clove is expecting to get more unlocked Galaxy Nexus in stock tomorrow. After paying the U.K. VAT tax it will run you about $800 before shipping.
A search of Google Shopping also turns up a handful of other vendors (most of which I've never heard of) offering the unlocked phone. I'd advise proceeding with caution and always checking out a seller using a service like ResellerRatings.
If you decide to hand over that big chunk of change to be one of the first sporting a new Ice Cream Sandwich phone, please let me know how it works out for you.