eBay
eBay currently has 67 active listings for the Oculus Rift CV (Consumer Version) 1, some of which are being sold for up to $1,800. That's three times the Oculus Rift's retail price of $599. But the Rift is already sold out through July, making it a hot commodity.
Some of these listings are for preorders, meaning the seller hasn't yet received their unit, but will ship to the buyer once they do. eBay doesn't explicitly ban the sale of preorder products, but does require the seller to follow a number of guidelines.
It's common for video game hardware to have a price spike at launch, with prices stabilizing as the product becomes more easily available. Excitement surrounding the Oculus has reached a fever pitch as the long-awaited device finally ships to customers who pre-ordered it and as the first, largely positive reviews are published.