The Asus ZenFone 2 is one of the more interesting unlocked phones to be announced lately, and you can secure yours right now on Amazon. A few more US retailers have product pages up, but it looks like it's just Amazon taking orders. The first round will ship on May 20th.
Now that the Amazon listing is live, we can find out exactly which variants come in which colors. The 16GB version with 2GB of RAM comes in black or silver only. That one is $199, by the way. The $299 ZenFone with 64GB of space and 4GB of RAM can be purchased in silver, gold, or red. Both versions of the ZenFone 2 are GSM/LTE devices with support for all the bands you need for North American carriers like AT&T and T-Mobile (and any associated MVNOs).
The price and color availability should be the same on B&H, Newegg, and Groupon when pre-orders are up. Amazon does offer Prime shipping, though. Canada? Nothing yet on your end, but Canada Computers has a page up with broken "buy" buttons. So that's something, I guess.