The Galaxy Note 4 was a beast of a device at launch, and as a direct result, it came with a beast of a price tag (the AT&T model in particular still goes for $850). It's the kind of phone that carriers offer for $300 on contact, which is enough money to outright own a decent piece of hardware these days.
Now that the Galaxy S6 exists and we're nearly a year out since the Note 4's launch, it's easier to get the 5.7-inch device at a more reasonable price. Today refurbished units are currently going on eBay for $400.
These are AT&T models, but they should still work with any GSM carrier. T-Mobile customers can expect LTE via band 4, but HSPA+ on the Un-carrier's network will only work in areas that have the 1900MHz re-farm active.
The seller is willing to mail boxes out to much of North America and Europe, along with Australia, but the options are pretty spotty elsewhere. Shipping is free, and only folks in California have to worry about a sales tax. You can place an order for a Note 4 in black or white.