HTC's new One M8 flagship has been out for three months. At this point in its product cycle, we wouldn't expect to see any dramatic discounts, except perhaps for on-contract phones. But one eBay vendor is bucking the trend, selling a new, factory-unlocked M8 for $549.99, a full $150 off the list price from HTC's own website. You can grab the phone and get free shipping to the United States, and unlike many eBay deals, the seller is shipping to a variety of countries around the world.
Just to be clear, this is a new phone, not refurbished, and not locked to any particular carrier. Assuming you use a standard GSM-LTE SIM card, you should be able to pop it in and get going almost anywhere in the world (with the notable exception of Verizon, Sprint, and a few other small CDMA throwbacks in the United States). The seller is offering the phone in its metallic silver (almost white) and grey versions - the gold model is out of stock. What a pity.
Most customers won't have to pay taxes on this One M8, unless you live in Texas, because the seller is shipping from Houston. (That's good, since sales tax in most states would have been ~$50.) At this price, what stock the seller has will probably be going quickly, so let your fingers do the walking over to eBay if you want one.